count back from the end of the array, and an index of -1 references the
last element.
- Any element of an array may be referenced using ${_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]}.
+ The += operator will append to an array variable when assigning using
+ the compound assignment syntax; see P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS above.
+
+ Any element of an array may be referenced using ${_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]}.
The braces are required to avoid conflicts with pathname expansion. If
- _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt is @\b@ or *\b*, the word expands to all members of _\bn_\ba_\bm_\be. These
- subscripts differ only when the word appears within double quotes. If
+ _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt is @\b@ or *\b*, the word expands to all members of _\bn_\ba_\bm_\be. These
+ subscripts differ only when the word appears within double quotes. If
the word is double-quoted, ${_\bn_\ba_\bm_\be[*]} expands to a single word with the
- value of each array member separated by the first character of the I\bIF\bFS\bS
+ value of each array member separated by the first character of the I\bIF\bFS\bS
special variable, and ${_\bn_\ba_\bm_\be[@]} expands each element of _\bn_\ba_\bm_\be to a sep-
- arate word. When there are no array members, ${_\bn_\ba_\bm_\be[@]} expands to
- nothing. If the double-quoted expansion occurs within a word, the ex-
+ arate word. When there are no array members, ${_\bn_\ba_\bm_\be[@]} expands to
+ nothing. If the double-quoted expansion occurs within a word, the ex-
pansion of the first parameter is joined with the beginning part of the
- original word, and the expansion of the last parameter is joined with
+ original word, and the expansion of the last parameter is joined with
the last part of the original word. This is analogous to the expansion
- of the special parameters *\b* and @\b@ (see S\bSp\bpe\bec\bci\bia\bal\bl P\bPa\bar\bra\bam\bme\bet\bte\ber\brs\bs above).
- ${#_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]} expands to the length of ${_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]}. If
+ of the special parameters *\b* and @\b@ (see S\bSp\bpe\bec\bci\bia\bal\bl P\bPa\bar\bra\bam\bme\bet\bte\ber\brs\bs above).
+ ${#_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]} expands to the length of ${_\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt]}. If
_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt is *\b* or @\b@, the expansion is the number of elements in the ar-
ray. If the _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt used to reference an element of an indexed array
- evaluates to a number less than zero, it is interpreted as relative to
- one greater than the maximum index of the array, so negative indices
+ evaluates to a number less than zero, it is interpreted as relative to
+ one greater than the maximum index of the array, so negative indices
count back from the end of the array, and an index of -1 references the
last element.
Referencing an array variable without a subscript is equivalent to ref-
- erencing the array with a subscript of 0. Any reference to a variable
+ erencing the array with a subscript of 0. Any reference to a variable
using a valid subscript is legal, and b\bba\bas\bsh\bh will create an array if nec-
essary.
- An array variable is considered set if a subscript has been assigned a
+ An array variable is considered set if a subscript has been assigned a
value. The null string is a valid value.
- It is possible to obtain the keys (indices) of an array as well as the
- values. ${!\b!_\bn_\ba_\bm_\be[_\b@]} and ${!\b!_\bn_\ba_\bm_\be[_\b*]} expand to the indices assigned in
+ It is possible to obtain the keys (indices) of an array as well as the
+ values. ${!\b!_\bn_\ba_\bm_\be[_\b@]} and ${!\b!_\bn_\ba_\bm_\be[_\b*]} expand to the indices assigned in
array variable _\bn_\ba_\bm_\be. The treatment when in double quotes is similar to
the expansion of the special parameters _\b@ and _\b* within double quotes.
The u\bun\bns\bse\bet\bt builtin is used to destroy arrays. u\bun\bns\bse\bet\bt _\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt] de-
stroys the array element at index _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt, for both indexed and asso-
- ciative arrays. Negative subscripts to indexed arrays are interpreted
- as described above. Unsetting the last element of an array variable
- does not unset the variable. u\bun\bns\bse\bet\bt _\bn_\ba_\bm_\be, where _\bn_\ba_\bm_\be is an array, re-
+ ciative arrays. Negative subscripts to indexed arrays are interpreted
+ as described above. Unsetting the last element of an array variable
+ does not unset the variable. u\bun\bns\bse\bet\bt _\bn_\ba_\bm_\be, where _\bn_\ba_\bm_\be is an array, re-
moves the entire array. u\bun\bns\bse\bet\bt _\bn_\ba_\bm_\be[_\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt], where _\bs_\bu_\bb_\bs_\bc_\br_\bi_\bp_\bt is *\b* or
@\b@, behaves differently depending on whether _\bn_\ba_\bm_\be is an indexed or asso-
- ciative array. If _\bn_\ba_\bm_\be is an associative array, this unsets the ele-
+ ciative array. If _\bn_\ba_\bm_\be is an associative array, this unsets the ele-
ment with subscript *\b* or @\b@. If _\bn_\ba_\bm_\be is an indexed array, unset removes
all of the elements but does not remove the array itself.
- When using a variable name with a subscript as an argument to a com-
- mand, such as with u\bun\bns\bse\bet\bt, without using the word expansion syntax de-
+ When using a variable name with a subscript as an argument to a com-
+ mand, such as with u\bun\bns\bse\bet\bt, without using the word expansion syntax de-
scribed above, the argument is subject to pathname expansion. If path-
name expansion is not desired, the argument should be quoted.
- The d\bde\bec\bcl\bla\bar\bre\be, l\blo\boc\bca\bal\bl, and r\bre\bea\bad\bdo\bon\bnl\bly\by builtins each accept a -\b-a\ba option to
- specify an indexed array and a -\b-A\bA option to specify an associative ar-
- ray. If both options are supplied, -\b-A\bA takes precedence. The r\bre\bea\bad\bd
- builtin accepts a -\b-a\ba option to assign a list of words read from the
+ The d\bde\bec\bcl\bla\bar\bre\be, l\blo\boc\bca\bal\bl, and r\bre\bea\bad\bdo\bon\bnl\bly\by builtins each accept a -\b-a\ba option to
+ specify an indexed array and a -\b-A\bA option to specify an associative ar-
+ ray. If both options are supplied, -\b-A\bA takes precedence. The r\bre\bea\bad\bd
+ builtin accepts a -\b-a\ba option to assign a list of words read from the
standard input to an array. The s\bse\bet\bt and d\bde\bec\bcl\bla\bar\bre\be builtins display array
values in a way that allows them to be reused as assignments.
E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN
Expansion is performed on the command line after it has been split into
- words. There are seven kinds of expansion performed: _\bb_\br_\ba_\bc_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn,
- _\bt_\bi_\bl_\bd_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br _\ba_\bn_\bd _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, _\bc_\bo_\bm_\bm_\ba_\bn_\bd _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\b-
+ words. There are seven kinds of expansion performed: _\bb_\br_\ba_\bc_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn,
+ _\bt_\bi_\bl_\bd_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br _\ba_\bn_\bd _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, _\bc_\bo_\bm_\bm_\ba_\bn_\bd _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\b-
_\bt_\bi_\bo_\bn, _\ba_\br_\bi_\bt_\bh_\bm_\be_\bt_\bi_\bc _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, _\bw_\bo_\br_\bd _\bs_\bp_\bl_\bi_\bt_\bt_\bi_\bn_\bg, and _\bp_\ba_\bt_\bh_\bn_\ba_\bm_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn.
The order of expansions is: brace expansion; tilde expansion, parameter
- and variable expansion, arithmetic expansion, and command substitution
- (done in a left-to-right fashion); word splitting; and pathname expan-
+ and variable expansion, arithmetic expansion, and command substitution
+ (done in a left-to-right fashion); word splitting; and pathname expan-
sion.
On systems that can support it, there is an additional expansion avail-
- able: _\bp_\br_\bo_\bc_\be_\bs_\bs _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\bt_\bi_\bo_\bn. This is performed at the same time as
- tilde, parameter, variable, and arithmetic expansion and command sub-
+ able: _\bp_\br_\bo_\bc_\be_\bs_\bs _\bs_\bu_\bb_\bs_\bt_\bi_\bt_\bu_\bt_\bi_\bo_\bn. This is performed at the same time as
+ tilde, parameter, variable, and arithmetic expansion and command sub-
stitution.
- After these expansions are performed, quote characters present in the
- original word are removed unless they have been quoted themselves
+ After these expansions are performed, quote characters present in the
+ original word are removed unless they have been quoted themselves
(_\bq_\bu_\bo_\bt_\be _\br_\be_\bm_\bo_\bv_\ba_\bl).
- Only brace expansion, word splitting, and pathname expansion can in-
- crease the number of words of the expansion; other expansions expand a
- single word to a single word. The only exceptions to this are the ex-
+ Only brace expansion, word splitting, and pathname expansion can in-
+ crease the number of words of the expansion; other expansions expand a
+ single word to a single word. The only exceptions to this are the ex-
pansions of "$\b$@\b@" and "$\b${\b{_\bn_\ba_\bm_\be[\b[@\b@]\b]}\b}", and, in most cases, $\b$*\b* and
$\b${\b{_\bn_\ba_\bm_\be[\b[*\b*]\b]}\b} as explained above (see P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS).
B\bBr\bra\bac\bce\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
_\bB_\br_\ba_\bc_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn is a mechanism by which arbitrary strings may be gener-
- ated. This mechanism is similar to _\bp_\ba_\bt_\bh_\bn_\ba_\bm_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, but the file-
+ ated. This mechanism is similar to _\bp_\ba_\bt_\bh_\bn_\ba_\bm_\be _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn, but the file-
names generated need not exist. Patterns to be brace expanded take the
form of an optional _\bp_\br_\be_\ba_\bm_\bb_\bl_\be, followed by either a series of comma-sep-
- arated strings or a sequence expression between a pair of braces, fol-
- lowed by an optional _\bp_\bo_\bs_\bt_\bs_\bc_\br_\bi_\bp_\bt. The preamble is prefixed to each
+ arated strings or a sequence expression between a pair of braces, fol-
+ lowed by an optional _\bp_\bo_\bs_\bt_\bs_\bc_\br_\bi_\bp_\bt. The preamble is prefixed to each
string contained within the braces, and the postscript is then appended
to each resulting string, expanding left to right.
- Brace expansions may be nested. The results of each expanded string
- are not sorted; left to right order is preserved. For example,
+ Brace expansions may be nested. The results of each expanded string
+ are not sorted; left to right order is preserved. For example,
a{\b{d,c,b}\b}e expands into `ade ace abe'.
- A sequence expression takes the form {\b{_\bx.\b..\b._\by[\b[.\b..\b._\bi_\bn_\bc_\br]\b]}\b}, where _\bx and _\by are
- either integers or single letters, and _\bi_\bn_\bc_\br, an optional increment, is
+ A sequence expression takes the form {\b{_\bx.\b..\b._\by[\b[.\b..\b._\bi_\bn_\bc_\br]\b]}\b}, where _\bx and _\by are
+ either integers or single letters, and _\bi_\bn_\bc_\br, an optional increment, is
an integer. When integers are supplied, the expression expands to each
- number between _\bx and _\by, inclusive. Supplied integers may be prefixed
- with _\b0 to force each term to have the same width. When either _\bx or _\by
- begins with a zero, the shell attempts to force all generated terms to
- contain the same number of digits, zero-padding where necessary. When
- letters are supplied, the expression expands to each character lexico-
- graphically between _\bx and _\by, inclusive, using the default C locale.
- Note that both _\bx and _\by must be of the same type (integer or letter).
- When the increment is supplied, it is used as the difference between
+ number between _\bx and _\by, inclusive. Supplied integers may be prefixed
+ with _\b0 to force each term to have the same width. When either _\bx or _\by
+ begins with a zero, the shell attempts to force all generated terms to
+ contain the same number of digits, zero-padding where necessary. When
+ letters are supplied, the expression expands to each character lexico-
+ graphically between _\bx and _\by, inclusive, using the default C locale.
+ Note that both _\bx and _\by must be of the same type (integer or letter).
+ When the increment is supplied, it is used as the difference between
each term. The default increment is 1 or -1 as appropriate.
Brace expansion is performed before any other expansions, and any char-
- acters special to other expansions are preserved in the result. It is
- strictly textual. B\bBa\bas\bsh\bh does not apply any syntactic interpretation to
+ acters special to other expansions are preserved in the result. It is
+ strictly textual. B\bBa\bas\bsh\bh does not apply any syntactic interpretation to
the context of the expansion or the text between the braces.
- A correctly-formed brace expansion must contain unquoted opening and
+ A correctly-formed brace expansion must contain unquoted opening and
closing braces, and at least one unquoted comma or a valid sequence ex-
pression. Any incorrectly formed brace expansion is left unchanged. A
- {\b{ or ,\b, may be quoted with a backslash to prevent its being considered
- part of a brace expression. To avoid conflicts with parameter expan-
+ {\b{ or ,\b, may be quoted with a backslash to prevent its being considered
+ part of a brace expression. To avoid conflicts with parameter expan-
sion, the string $\b${\b{ is not considered eligible for brace expansion, and
inhibits brace expansion until the closing }\b}.
or
chown root /usr/{ucb/{ex,edit},lib/{ex?.?*,how_ex}}
- Brace expansion introduces a slight incompatibility with historical
- versions of s\bsh\bh. s\bsh\bh does not treat opening or closing braces specially
- when they appear as part of a word, and preserves them in the output.
- B\bBa\bas\bsh\bh removes braces from words as a consequence of brace expansion.
- For example, a word entered to s\bsh\bh as _\bf_\bi_\bl_\be_\b{_\b1_\b,_\b2_\b} appears identically in
- the output. The same word is output as _\bf_\bi_\bl_\be_\b1 _\bf_\bi_\bl_\be_\b2 after expansion by
- b\bba\bas\bsh\bh. If strict compatibility with s\bsh\bh is desired, start b\bba\bas\bsh\bh with the
+ Brace expansion introduces a slight incompatibility with historical
+ versions of s\bsh\bh. s\bsh\bh does not treat opening or closing braces specially
+ when they appear as part of a word, and preserves them in the output.
+ B\bBa\bas\bsh\bh removes braces from words as a consequence of brace expansion.
+ For example, a word entered to s\bsh\bh as _\bf_\bi_\bl_\be_\b{_\b1_\b,_\b2_\b} appears identically in
+ the output. The same word is output as _\bf_\bi_\bl_\be_\b1 _\bf_\bi_\bl_\be_\b2 after expansion by
+ b\bba\bas\bsh\bh. If strict compatibility with s\bsh\bh is desired, start b\bba\bas\bsh\bh with the
+\b+B\bB option or disable brace expansion with the +\b+B\bB option to the s\bse\bet\bt com-
mand (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).
T\bTi\bil\bld\bde\be E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
- If a word begins with an unquoted tilde character (`~\b~'), all of the
- characters preceding the first unquoted slash (or all characters, if
- there is no unquoted slash) are considered a _\bt_\bi_\bl_\bd_\be_\b-_\bp_\br_\be_\bf_\bi_\bx. If none of
- the characters in the tilde-prefix are quoted, the characters in the
- tilde-prefix following the tilde are treated as a possible _\bl_\bo_\bg_\bi_\bn _\bn_\ba_\bm_\be.
- If this login name is the null string, the tilde is replaced with the
- value of the shell parameter H\bHO\bOM\bME\bE. If H\bHO\bOM\bME\bE is unset, the home direc-
- tory of the user executing the shell is substituted instead. Other-
- wise, the tilde-prefix is replaced with the home directory associated
+ If a word begins with an unquoted tilde character (`~\b~'), all of the
+ characters preceding the first unquoted slash (or all characters, if
+ there is no unquoted slash) are considered a _\bt_\bi_\bl_\bd_\be_\b-_\bp_\br_\be_\bf_\bi_\bx. If none of
+ the characters in the tilde-prefix are quoted, the characters in the
+ tilde-prefix following the tilde are treated as a possible _\bl_\bo_\bg_\bi_\bn _\bn_\ba_\bm_\be.
+ If this login name is the null string, the tilde is replaced with the
+ value of the shell parameter H\bHO\bOM\bME\bE. If H\bHO\bOM\bME\bE is unset, the home direc-
+ tory of the user executing the shell is substituted instead. Other-
+ wise, the tilde-prefix is replaced with the home directory associated
with the specified login name.
- If the tilde-prefix is a `~+', the value of the shell variable P\bPW\bWD\bD re-
- places the tilde-prefix. If the tilde-prefix is a `~-', the value of
- the shell variable O\bOL\bLD\bDP\bPW\bWD\bD, if it is set, is substituted. If the char-
- acters following the tilde in the tilde-prefix consist of a number _\bN,
- optionally prefixed by a `+' or a `-', the tilde-prefix is replaced
+ If the tilde-prefix is a `~+', the value of the shell variable P\bPW\bWD\bD re-
+ places the tilde-prefix. If the tilde-prefix is a `~-', the value of
+ the shell variable O\bOL\bLD\bDP\bPW\bWD\bD, if it is set, is substituted. If the char-
+ acters following the tilde in the tilde-prefix consist of a number _\bN,
+ optionally prefixed by a `+' or a `-', the tilde-prefix is replaced
with the corresponding element from the directory stack, as it would be
displayed by the d\bdi\bir\brs\bs builtin invoked with the tilde-prefix as an argu-
- ment. If the characters following the tilde in the tilde-prefix con-
+ ment. If the characters following the tilde in the tilde-prefix con-
sist of a number without a leading `+' or `-', `+' is assumed.
If the login name is invalid, or the tilde expansion fails, the word is
Each variable assignment is checked for unquoted tilde-prefixes immedi-
ately following a :\b: or the first =\b=. In these cases, tilde expansion is
also performed. Consequently, one may use filenames with tildes in as-
- signments to P\bPA\bAT\bTH\bH, M\bMA\bAI\bIL\bLP\bPA\bAT\bTH\bH, and C\bCD\bDP\bPA\bAT\bTH\bH, and the shell assigns the ex-
+ signments to P\bPA\bAT\bTH\bH, M\bMA\bAI\bIL\bLP\bPA\bAT\bTH\bH, and C\bCD\bDP\bPA\bAT\bTH\bH, and the shell assigns the ex-
panded value.
- Bash also performs tilde expansion on words satisfying the conditions
+ Bash also performs tilde expansion on words satisfying the conditions
of variable assignments (as described above under P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS) when they
- appear as arguments to simple commands. Bash does not do this, except
+ appear as arguments to simple commands. Bash does not do this, except
for the _\bd_\be_\bc_\bl_\ba_\br_\ba_\bt_\bi_\bo_\bn commands listed above, when in _\bp_\bo_\bs_\bi_\bx _\bm_\bo_\bd_\be.
P\bPa\bar\bra\bam\bme\bet\bte\ber\br E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn
The `$\b$' character introduces parameter expansion, command substitution,
- or arithmetic expansion. The parameter name or symbol to be expanded
- may be enclosed in braces, which are optional but serve to protect the
- variable to be expanded from characters immediately following it which
+ or arithmetic expansion. The parameter name or symbol to be expanded
+ may be enclosed in braces, which are optional but serve to protect the
+ variable to be expanded from characters immediately following it which
could be interpreted as part of the name.
- When braces are used, the matching ending brace is the first `}\b}' not
+ When braces are used, the matching ending brace is the first `}\b}' not
escaped by a backslash or within a quoted string, and not within an em-
- bedded arithmetic expansion, command substitution, or parameter expan-
+ bedded arithmetic expansion, command substitution, or parameter expan-
sion.
${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br}
- The value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is substituted. The braces are required
- when _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is a positional parameter with more than one
+ The value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is substituted. The braces are required
+ when _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is a positional parameter with more than one
digit, or when _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is followed by a character which is not
to be interpreted as part of its name. The _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is a shell
- parameter as described above P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS) or an array reference
+ parameter as described above P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS) or an array reference
(A\bAr\brr\bra\bay\bys\bs).
- If the first character of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an exclamation point (!\b!), and
+ If the first character of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an exclamation point (!\b!), and
_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is not a _\bn_\ba_\bm_\be_\br_\be_\bf, it introduces a level of indirection. B\bBa\bas\bsh\bh
uses the value formed by expanding the rest of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br as the new _\bp_\ba_\b-
- _\br_\ba_\bm_\be_\bt_\be_\br; this is then expanded and that value is used in the rest of
- the expansion, rather than the expansion of the original _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br.
+ _\br_\ba_\bm_\be_\bt_\be_\br; this is then expanded and that value is used in the rest of
+ the expansion, rather than the expansion of the original _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br.
This is known as _\bi_\bn_\bd_\bi_\br_\be_\bc_\bt _\be_\bx_\bp_\ba_\bn_\bs_\bi_\bo_\bn. The value is subject to tilde ex-
- pansion, parameter expansion, command substitution, and arithmetic ex-
- pansion. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is a nameref, this expands to the name of the
- parameter referenced by _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br instead of performing the complete
- indirect expansion. The exceptions to this are the expansions of
- ${!\b!_\bp_\br_\be_\bf_\bi_\bx*\b*} and ${!\b!_\bn_\ba_\bm_\be[_\b@]} described below. The exclamation point
- must immediately follow the left brace in order to introduce indirec-
+ pansion, parameter expansion, command substitution, and arithmetic ex-
+ pansion. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is a nameref, this expands to the name of the
+ parameter referenced by _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br instead of performing the complete
+ indirect expansion. The exceptions to this are the expansions of
+ ${!\b!_\bp_\br_\be_\bf_\bi_\bx*\b*} and ${!\b!_\bn_\ba_\bm_\be[_\b@]} described below. The exclamation point
+ must immediately follow the left brace in order to introduce indirec-
tion.
In each of the cases below, _\bw_\bo_\br_\bd is subject to tilde expansion, parame-
ter expansion, command substitution, and arithmetic expansion.
When not performing substring expansion, using the forms documented be-
- low (e.g., :\b:-\b-), b\bba\bas\bsh\bh tests for a parameter that is unset or null.
- Omitting the colon results in a test only for a parameter that is un-
+ low (e.g., :\b:-\b-), b\bba\bas\bsh\bh tests for a parameter that is unset or null.
+ Omitting the colon results in a test only for a parameter that is un-
set.
${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:-\b-_\bw_\bo_\br_\bd}
- U\bUs\bse\be D\bDe\bef\bfa\bau\bul\blt\bt V\bVa\bal\blu\bue\bes\bs. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is unset or null, the expan-
- sion of _\bw_\bo_\br_\bd is substituted. Otherwise, the value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br
+ U\bUs\bse\be D\bDe\bef\bfa\bau\bul\blt\bt V\bVa\bal\blu\bue\bes\bs. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is unset or null, the expan-
+ sion of _\bw_\bo_\br_\bd is substituted. Otherwise, the value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br
is substituted.
${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:=\b=_\bw_\bo_\br_\bd}
- A\bAs\bss\bsi\big\bgn\bn D\bDe\bef\bfa\bau\bul\blt\bt V\bVa\bal\blu\bue\bes\bs. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is unset or null, the ex-
- pansion of _\bw_\bo_\br_\bd is assigned to _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br. The value of _\bp_\ba_\br_\ba_\bm_\be_\b-
- _\bt_\be_\br is then substituted. Positional parameters and special pa-
+ A\bAs\bss\bsi\big\bgn\bn D\bDe\bef\bfa\bau\bul\blt\bt V\bVa\bal\blu\bue\bes\bs. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is unset or null, the ex-
+ pansion of _\bw_\bo_\br_\bd is assigned to _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br. The value of _\bp_\ba_\br_\ba_\bm_\be_\b-
+ _\bt_\be_\br is then substituted. Positional parameters and special pa-
rameters may not be assigned to in this way.
${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:?\b?_\bw_\bo_\br_\bd}
- D\bDi\bis\bsp\bpl\bla\bay\by E\bEr\brr\bro\bor\br i\bif\bf N\bNu\bul\bll\bl o\bor\br U\bUn\bns\bse\bet\bt. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is null or unset,
- the expansion of _\bw_\bo_\br_\bd (or a message to that effect if _\bw_\bo_\br_\bd is
- not present) is written to the standard error and the shell, if
+ D\bDi\bis\bsp\bpl\bla\bay\by E\bEr\brr\bro\bor\br i\bif\bf N\bNu\bul\bll\bl o\bor\br U\bUn\bns\bse\bet\bt. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is null or unset,
+ the expansion of _\bw_\bo_\br_\bd (or a message to that effect if _\bw_\bo_\br_\bd is
+ not present) is written to the standard error and the shell, if
it is not interactive, exits. Otherwise, the value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br
is substituted.
${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:+\b+_\bw_\bo_\br_\bd}
- U\bUs\bse\be A\bAl\blt\bte\ber\brn\bna\bat\bte\be V\bVa\bal\blu\bue\be. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is null or unset, nothing is
+ U\bUs\bse\be A\bAl\blt\bte\ber\brn\bna\bat\bte\be V\bVa\bal\blu\bue\be. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is null or unset, nothing is
substituted, otherwise the expansion of _\bw_\bo_\br_\bd is substituted.
${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:_\bo_\bf_\bf_\bs_\be_\bt}
${_\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br:\b:_\bo_\bf_\bf_\bs_\be_\bt:\b:_\bl_\be_\bn_\bg_\bt_\bh}
- S\bSu\bub\bbs\bst\btr\bri\bin\bng\bg E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn. Expands to up to _\bl_\be_\bn_\bg_\bt_\bh characters of the
- value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br starting at the character specified by _\bo_\bf_\bf_\b-
- _\bs_\be_\bt. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@, an indexed array subscripted by @\b@ or *\b*,
- or an associative array name, the results differ as described
- below. If _\bl_\be_\bn_\bg_\bt_\bh is omitted, expands to the substring of the
- value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br starting at the character specified by _\bo_\bf_\bf_\bs_\be_\bt
- and extending to the end of the value. _\bl_\be_\bn_\bg_\bt_\bh and _\bo_\bf_\bf_\bs_\be_\bt are
- arithmetic expressions (see A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN below).
-
- If _\bo_\bf_\bf_\bs_\be_\bt evaluates to a number less than zero, the value is
+ S\bSu\bub\bbs\bst\btr\bri\bin\bng\bg E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn. Expands to up to _\bl_\be_\bn_\bg_\bt_\bh characters of the
+ value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br starting at the character specified by _\bo_\bf_\bf_\b-
+ _\bs_\be_\bt. If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@ or *\b*, an indexed array subscripted by @\b@
+ or *\b*, or an associative array name, the results differ as de-
+ scribed below. If _\bl_\be_\bn_\bg_\bt_\bh is omitted, expands to the substring
+ of the value of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br starting at the character specified by
+ _\bo_\bf_\bf_\bs_\be_\bt and extending to the end of the value. _\bl_\be_\bn_\bg_\bt_\bh and _\bo_\bf_\bf_\bs_\be_\bt
+ are arithmetic expressions (see A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN below).
+
+ If _\bo_\bf_\bf_\bs_\be_\bt evaluates to a number less than zero, the value is
used as an offset in characters from the end of the value of _\bp_\ba_\b-
- _\br_\ba_\bm_\be_\bt_\be_\br. If _\bl_\be_\bn_\bg_\bt_\bh evaluates to a number less than zero, it is
+ _\br_\ba_\bm_\be_\bt_\be_\br. If _\bl_\be_\bn_\bg_\bt_\bh evaluates to a number less than zero, it is
interpreted as an offset in characters from the end of the value
- of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br rather than a number of characters, and the expan-
- sion is the characters between _\bo_\bf_\bf_\bs_\be_\bt and that result. Note
- that a negative offset must be separated from the colon by at
+ of _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br rather than a number of characters, and the expan-
+ sion is the characters between _\bo_\bf_\bf_\bs_\be_\bt and that result. Note
+ that a negative offset must be separated from the colon by at
least one space to avoid being confused with the :\b:-\b- expansion.
- If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@, the result is _\bl_\be_\bn_\bg_\bt_\bh positional parameters
- beginning at _\bo_\bf_\bf_\bs_\be_\bt. A negative _\bo_\bf_\bf_\bs_\be_\bt is taken relative to one
- greater than the greatest positional parameter, so an offset of
- -1 evaluates to the last positional parameter. It is an expan-
- sion error if _\bl_\be_\bn_\bg_\bt_\bh evaluates to a number less than zero.
+ If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is @\b@ or *\b*, the result is _\bl_\be_\bn_\bg_\bt_\bh positional parame-
+ ters beginning at _\bo_\bf_\bf_\bs_\be_\bt. A negative _\bo_\bf_\bf_\bs_\be_\bt is taken relative
+ to one greater than the greatest positional parameter, so an
+ offset of -1 evaluates to the last positional parameter. It is
+ an expansion error if _\bl_\be_\bn_\bg_\bt_\bh evaluates to a number less than
+ zero.
If _\bp_\ba_\br_\ba_\bm_\be_\bt_\be_\br is an indexed array name subscripted by @ or *, the
result is the _\bl_\be_\bn_\bg_\bt_\bh members of the array beginning with ${_\bp_\ba_\b-
option has been enabled.
Variables local to the function may be declared with the l\blo\boc\bca\bal\bl builtin
- command. Ordinarily, variables and their values are shared between the
- function and its caller. If a variable is declared l\blo\boc\bca\bal\bl, the vari-
- able's visible scope is restricted to that function and its children
- (including the functions it calls). Local variables "shadow" variables
- with the same name declared at previous scopes. For instance, a local
- variable declared in a function hides a global variable of the same
- name: references and assignments refer to the local variable, leaving
- the global variable unmodified. When the function returns, the global
- variable is once again visible.
+ command (_\bl_\bo_\bc_\ba_\bl _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be_\bs). Ordinarily, variables and their values are
+ shared between the function and its caller. If a variable is declared
+ l\blo\boc\bca\bal\bl, the variable's visible scope is restricted to that function and
+ its children (including the functions it calls).
+
+ In the following description, the _\bc_\bu_\br_\br_\be_\bn_\bt _\bs_\bc_\bo_\bp_\be is a currently- execut-
+ ing function. Previous scopes consist of that function's caller and so
+ on, back to the "global" scope, where the shell is not executing any
+ shell function. Consequently, a local variable at the current scope is
+ a variable declared using the l\blo\boc\bca\bal\bl or d\bde\bec\bcl\bla\bar\bre\be builtins in the function
+ that is currently executing.
+
+ Local variables "shadow" variables with the same name declared at pre-
+ vious scopes. For instance, a local variable declared in a function
+ hides a global variable of the same name: references and assignments
+ refer to the local variable, leaving the global variable unmodified.
+ When the function returns, the global variable is once again visible.
The shell uses _\bd_\by_\bn_\ba_\bm_\bi_\bc _\bs_\bc_\bo_\bp_\bi_\bn_\bg to control a variable's visibility
within functions. With dynamic scoping, visible variables and their
is local to the current scope, u\bun\bns\bse\bet\bt will unset it; otherwise the unset
will refer to the variable found in any calling scope as described
above. If a variable at the current local scope is unset, it will re-
- main so until it is reset in that scope or until the function returns.
- Once the function returns, any instance of the variable at a previous
- scope will become visible. If the unset acts on a variable at a previ-
- ous scope, any instance of a variable with that name that had been
- shadowed will become visible.
-
- The F\bFU\bUN\bNC\bCN\bNE\bES\bST\bT variable, if set to a numeric value greater than 0, de-
- fines a maximum function nesting level. Function invocations that ex-
+ main so (appearing as unset) until it is reset in that scope or until
+ the function returns. Once the function returns, any instance of the
+ variable at a previous scope will become visible. If the unset acts on
+ a variable at a previous scope, any instance of a variable with that
+ name that had been shadowed will become visible (see below how the l\blo\bo-\b-
+ c\bca\bal\blv\bva\bar\br_\b_u\bun\bns\bse\bet\bt shell option changes this behavior).
+
+ The F\bFU\bUN\bNC\bCN\bNE\bES\bST\bT variable, if set to a numeric value greater than 0, de-
+ fines a maximum function nesting level. Function invocations that ex-
ceed the limit cause the entire command to abort.
- If the builtin command r\bre\bet\btu\bur\brn\bn is executed in a function, the function
- completes and execution resumes with the next command after the func-
+ If the builtin command r\bre\bet\btu\bur\brn\bn is executed in a function, the function
+ completes and execution resumes with the next command after the func-
tion call. Any command associated with the R\bRE\bET\bTU\bUR\bRN\bN trap is executed be-
- fore execution resumes. When a function completes, the values of the
- positional parameters and the special parameter #\b# are restored to the
+ fore execution resumes. When a function completes, the values of the
+ positional parameters and the special parameter #\b# are restored to the
values they had prior to the function's execution.
- Function names and definitions may be listed with the -\b-f\bf option to the
+ Function names and definitions may be listed with the -\b-f\bf option to the
d\bde\bec\bcl\bla\bar\bre\be or t\bty\byp\bpe\bes\bse\bet\bt builtin commands. The -\b-F\bF option to d\bde\bec\bcl\bla\bar\bre\be or t\bty\byp\bpe\be-\b-
- s\bse\bet\bt will list the function names only (and optionally the source file
- and line number, if the e\bex\bxt\btd\bde\beb\bbu\bug\bg shell option is enabled). Functions
- may be exported so that child shell processes (those created when exe-
- cuting a separate shell invocation) automatically have them defined
+ s\bse\bet\bt will list the function names only (and optionally the source file
+ and line number, if the e\bex\bxt\btd\bde\beb\bbu\bug\bg shell option is enabled). Functions
+ may be exported so that child shell processes (those created when exe-
+ cuting a separate shell invocation) automatically have them defined
with the -\b-f\bf option to the e\bex\bxp\bpo\bor\brt\bt builtin. A function definition may be
deleted using the -\b-f\bf option to the u\bun\bns\bse\bet\bt builtin.
Functions may be recursive. The F\bFU\bUN\bNC\bCN\bNE\bES\bST\bT variable may be used to limit
- the depth of the function call stack and restrict the number of func-
+ the depth of the function call stack and restrict the number of func-
tion invocations. By default, no limit is imposed on the number of re-
cursive calls.
A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN
- The shell allows arithmetic expressions to be evaluated, under certain
- circumstances (see the l\ble\bet\bt and d\bde\bec\bcl\bla\bar\bre\be builtin commands, the (\b((\b( com-
+ The shell allows arithmetic expressions to be evaluated, under certain
+ circumstances (see the l\ble\bet\bt and d\bde\bec\bcl\bla\bar\bre\be builtin commands, the (\b((\b( com-
pound command, and A\bAr\bri\bit\bth\bhm\bme\bet\bti\bic\bc E\bEx\bxp\bpa\ban\bns\bsi\bio\bon\bn). Evaluation is done in fixed-
- width integers with no check for overflow, though division by 0 is
- trapped and flagged as an error. The operators and their precedence,
- associativity, and values are the same as in the C language. The fol-
+ width integers with no check for overflow, though division by 0 is
+ trapped and flagged as an error. The operators and their precedence,
+ associativity, and values are the same as in the C language. The fol-
lowing list of operators is grouped into levels of equal-precedence op-
erators. The levels are listed in order of decreasing precedence.
_\be_\bx_\bp_\br_\b1 ,\b, _\be_\bx_\bp_\br_\b2
comma
- Shell variables are allowed as operands; parameter expansion is per-
+ Shell variables are allowed as operands; parameter expansion is per-
formed before the expression is evaluated. Within an expression, shell
- variables may also be referenced by name without using the parameter
- expansion syntax. A shell variable that is null or unset evaluates to
+ variables may also be referenced by name without using the parameter
+ expansion syntax. A shell variable that is null or unset evaluates to
0 when referenced by name without using the parameter expansion syntax.
- The value of a variable is evaluated as an arithmetic expression when
- it is referenced, or when a variable which has been given the _\bi_\bn_\bt_\be_\bg_\be_\br
+ The value of a variable is evaluated as an arithmetic expression when
+ it is referenced, or when a variable which has been given the _\bi_\bn_\bt_\be_\bg_\be_\br
attribute using d\bde\bec\bcl\bla\bar\bre\be -\b-i\bi is assigned a value. A null value evaluates
- to 0. A shell variable need not have its _\bi_\bn_\bt_\be_\bg_\be_\br attribute turned on
+ to 0. A shell variable need not have its _\bi_\bn_\bt_\be_\bg_\be_\br attribute turned on
to be used in an expression.
Integer constants follow the C language definition, without suffixes or
character constants. Constants with a leading 0 are interpreted as oc-
- tal numbers. A leading 0x or 0X denotes hexadecimal. Otherwise, num-
- bers take the form [_\bb_\ba_\bs_\be_\b#]n, where the optional _\bb_\ba_\bs_\be is a decimal num-
- ber between 2 and 64 representing the arithmetic base, and _\bn is a num-
- ber in that base. If _\bb_\ba_\bs_\be_\b# is omitted, then base 10 is used. When
+ tal numbers. A leading 0x or 0X denotes hexadecimal. Otherwise, num-
+ bers take the form [_\bb_\ba_\bs_\be_\b#]n, where the optional _\bb_\ba_\bs_\be is a decimal num-
+ ber between 2 and 64 representing the arithmetic base, and _\bn is a num-
+ ber in that base. If _\bb_\ba_\bs_\be_\b# is omitted, then base 10 is used. When
specifying _\bn, if a non-digit is required, the digits greater than 9 are
- represented by the lowercase letters, the uppercase letters, @, and _,
- in that order. If _\bb_\ba_\bs_\be is less than or equal to 36, lowercase and up-
- percase letters may be used interchangeably to represent numbers be-
+ represented by the lowercase letters, the uppercase letters, @, and _,
+ in that order. If _\bb_\ba_\bs_\be is less than or equal to 36, lowercase and up-
+ percase letters may be used interchangeably to represent numbers be-
tween 10 and 35.
- Operators are evaluated in order of precedence. Sub-expressions in
- parentheses are evaluated first and may override the precedence rules
+ Operators are evaluated in order of precedence. Sub-expressions in
+ parentheses are evaluated first and may override the precedence rules
above.
C\bCO\bON\bND\bDI\bIT\bTI\bIO\bON\bNA\bAL\bL E\bEX\bXP\bPR\bRE\bES\bSS\bSI\bIO\bON\bNS\bS
- Conditional expressions are used by the [\b[[\b[ compound command and the
- t\bte\bes\bst\bt and [\b[ builtin commands to test file attributes and perform string
- and arithmetic comparisons. The t\bte\bes\bst\bt and [\b[ commands determine their
- behavior based on the number of arguments; see the descriptions of
+ Conditional expressions are used by the [\b[[\b[ compound command and the
+ t\bte\bes\bst\bt and [\b[ builtin commands to test file attributes and perform string
+ and arithmetic comparisons. The t\bte\bes\bst\bt and [\b[ commands determine their
+ behavior based on the number of arguments; see the descriptions of
those commands for any other command-specific actions.
- Expressions are formed from the following unary or binary primaries.
- B\bBa\bas\bsh\bh handles several filenames specially when they are used in expres-
+ Expressions are formed from the following unary or binary primaries.
+ B\bBa\bas\bsh\bh handles several filenames specially when they are used in expres-
sions. If the operating system on which b\bba\bas\bsh\bh is running provides these
- special files, bash will use them; otherwise it will emulate them in-
- ternally with this behavior: If any _\bf_\bi_\bl_\be argument to one of the pri-
+ special files, bash will use them; otherwise it will emulate them in-
+ ternally with this behavior: If any _\bf_\bi_\bl_\be argument to one of the pri-
maries is of the form _\b/_\bd_\be_\bv_\b/_\bf_\bd_\b/_\bn, then file descriptor _\bn is checked. If
- the _\bf_\bi_\bl_\be argument to one of the primaries is one of _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\bi_\bn,
- _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\bo_\bu_\bt, or _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\be_\br_\br, file descriptor 0, 1, or 2, respectively,
+ the _\bf_\bi_\bl_\be argument to one of the primaries is one of _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\bi_\bn,
+ _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\bo_\bu_\bt, or _\b/_\bd_\be_\bv_\b/_\bs_\bt_\bd_\be_\br_\br, file descriptor 0, 1, or 2, respectively,
is checked.
Unless otherwise specified, primaries that operate on files follow sym-
bolic links and operate on the target of the link, rather than the link
itself.
- When used with [\b[[\b[, the <\b< and >\b> operators sort lexicographically using
+ When used with [\b[[\b[, the <\b< and >\b> operators sort lexicographically using
the current locale. The t\bte\bes\bst\bt command sorts using ASCII ordering.
-\b-a\ba _\bf_\bi_\bl_\be
-\b-L\bL _\bf_\bi_\bl_\be
True if _\bf_\bi_\bl_\be exists and is a symbolic link.
-\b-N\bN _\bf_\bi_\bl_\be
- True if _\bf_\bi_\bl_\be exists and has been modified since it was last
+ True if _\bf_\bi_\bl_\be exists and has been modified since it was last
read.
-\b-O\bO _\bf_\bi_\bl_\be
True if _\bf_\bi_\bl_\be exists and is owned by the effective user id.
-\b-S\bS _\bf_\bi_\bl_\be
True if _\bf_\bi_\bl_\be exists and is a socket.
_\bf_\bi_\bl_\be_\b1 -\b-e\bef\bf _\bf_\bi_\bl_\be_\b2
- True if _\bf_\bi_\bl_\be_\b1 and _\bf_\bi_\bl_\be_\b2 refer to the same device and inode num-
+ True if _\bf_\bi_\bl_\be_\b1 and _\bf_\bi_\bl_\be_\b2 refer to the same device and inode num-
bers.
_\bf_\bi_\bl_\be_\b1 -n\bnt\bt _\bf_\bi_\bl_\be_\b2
- True if _\bf_\bi_\bl_\be_\b1 is newer (according to modification date) than
+ True if _\bf_\bi_\bl_\be_\b1 is newer (according to modification date) than
_\bf_\bi_\bl_\be_\b2, or if _\bf_\bi_\bl_\be_\b1 exists and _\bf_\bi_\bl_\be_\b2 does not.
_\bf_\bi_\bl_\be_\b1 -o\bot\bt _\bf_\bi_\bl_\be_\b2
- True if _\bf_\bi_\bl_\be_\b1 is older than _\bf_\bi_\bl_\be_\b2, or if _\bf_\bi_\bl_\be_\b2 exists and _\bf_\bi_\bl_\be_\b1
+ True if _\bf_\bi_\bl_\be_\b1 is older than _\bf_\bi_\bl_\be_\b2, or if _\bf_\bi_\bl_\be_\b2 exists and _\bf_\bi_\bl_\be_\b1
does not.
-\b-o\bo _\bo_\bp_\bt_\bn_\ba_\bm_\be
- True if the shell option _\bo_\bp_\bt_\bn_\ba_\bm_\be is enabled. See the list of
- options under the description of the -\b-o\bo option to the s\bse\bet\bt
+ True if the shell option _\bo_\bp_\bt_\bn_\ba_\bm_\be is enabled. See the list of
+ options under the description of the -\b-o\bo option to the s\bse\bet\bt
builtin below.
-\b-v\bv _\bv_\ba_\br_\bn_\ba_\bm_\be
- True if the shell variable _\bv_\ba_\br_\bn_\ba_\bm_\be is set (has been assigned a
+ True if the shell variable _\bv_\ba_\br_\bn_\ba_\bm_\be is set (has been assigned a
value).
-\b-R\bR _\bv_\ba_\br_\bn_\ba_\bm_\be
- True if the shell variable _\bv_\ba_\br_\bn_\ba_\bm_\be is set and is a name refer-
+ True if the shell variable _\bv_\ba_\br_\bn_\ba_\bm_\be is set and is a name refer-
ence.
-\b-z\bz _\bs_\bt_\br_\bi_\bn_\bg
True if the length of _\bs_\bt_\br_\bi_\bn_\bg is zero.
_\bs_\bt_\br_\bi_\bn_\bg_\b1 =\b==\b= _\bs_\bt_\br_\bi_\bn_\bg_\b2
_\bs_\bt_\br_\bi_\bn_\bg_\b1 =\b= _\bs_\bt_\br_\bi_\bn_\bg_\b2
- True if the strings are equal. =\b= should be used with the t\bte\bes\bst\bt
- command for POSIX conformance. When used with the [\b[[\b[ command,
+ True if the strings are equal. =\b= should be used with the t\bte\bes\bst\bt
+ command for POSIX conformance. When used with the [\b[[\b[ command,
this performs pattern matching as described above (C\bCo\bom\bmp\bpo\bou\bun\bnd\bd C\bCo\bom\bm-\b-
m\bma\ban\bnd\bds\bs).
True if _\bs_\bt_\br_\bi_\bn_\bg_\b1 sorts after _\bs_\bt_\br_\bi_\bn_\bg_\b2 lexicographically.
_\ba_\br_\bg_\b1 O\bOP\bP _\ba_\br_\bg_\b2
- O\bOP\bP is one of -\b-e\beq\bq, -\b-n\bne\be, -\b-l\blt\bt, -\b-l\ble\be, -\b-g\bgt\bt, or -\b-g\bge\be. These arithmetic
- binary operators return true if _\ba_\br_\bg_\b1 is equal to, not equal to,
- less than, less than or equal to, greater than, or greater than
- or equal to _\ba_\br_\bg_\b2, respectively. _\bA_\br_\bg_\b1 and _\ba_\br_\bg_\b2 may be positive
- or negative integers. When used with the [\b[[\b[ command, _\bA_\br_\bg_\b1 and
- _\bA_\br_\bg_\b2 are evaluated as arithmetic expressions (see A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC
+ O\bOP\bP is one of -\b-e\beq\bq, -\b-n\bne\be, -\b-l\blt\bt, -\b-l\ble\be, -\b-g\bgt\bt, or -\b-g\bge\be. These arithmetic
+ binary operators return true if _\ba_\br_\bg_\b1 is equal to, not equal to,
+ less than, less than or equal to, greater than, or greater than
+ or equal to _\ba_\br_\bg_\b2, respectively. _\bA_\br_\bg_\b1 and _\ba_\br_\bg_\b2 may be positive
+ or negative integers. When used with the [\b[[\b[ command, _\bA_\br_\bg_\b1 and
+ _\bA_\br_\bg_\b2 are evaluated as arithmetic expressions (see A\bAR\bRI\bIT\bTH\bHM\bME\bET\bTI\bIC\bC
E\bEV\bVA\bAL\bLU\bUA\bAT\bTI\bIO\bON\bN above).
S\bSI\bIM\bMP\bPL\bLE\bE C\bCO\bOM\bMM\bMA\bAN\bND\bD E\bEX\bXP\bPA\bAN\bNS\bSI\bIO\bON\bN
When a simple command is executed, the shell performs the following ex-
- pansions, assignments, and redirections, from left to right, in the
+ pansions, assignments, and redirections, from left to right, in the
following order.
- 1. The words that the parser has marked as variable assignments
- (those preceding the command name) and redirections are saved
+ 1. The words that the parser has marked as variable assignments
+ (those preceding the command name) and redirections are saved
for later processing.
- 2. The words that are not variable assignments or redirections are
- expanded. If any words remain after expansion, the first word
- is taken to be the name of the command and the remaining words
+ 2. The words that are not variable assignments or redirections are
+ expanded. If any words remain after expansion, the first word
+ is taken to be the name of the command and the remaining words
are the arguments.
3. Redirections are performed as described above under R\bRE\bED\bDI\bIR\bRE\bEC\bCT\bTI\bIO\bON\bN.
4. The text after the =\b= in each variable assignment undergoes tilde
expansion, parameter expansion, command substitution, arithmetic
- expansion, and quote removal before being assigned to the vari-
+ expansion, and quote removal before being assigned to the vari-
able.
If no command name results, the variable assignments affect the current
- shell environment. In the case of such a command (one that consists
- only of assignment statements and redirections), assignment statements
- are performed before redirections. Otherwise, the variables are added
- to the environment of the executed command and do not affect the cur-
+ shell environment. In the case of such a command (one that consists
+ only of assignment statements and redirections), assignment statements
+ are performed before redirections. Otherwise, the variables are added
+ to the environment of the executed command and do not affect the cur-
rent shell environment. If any of the assignments attempts to assign a
- value to a readonly variable, an error occurs, and the command exits
+ value to a readonly variable, an error occurs, and the command exits
with a non-zero status.
- If no command name results, redirections are performed, but do not af-
- fect the current shell environment. A redirection error causes the
+ If no command name results, redirections are performed, but do not af-
+ fect the current shell environment. A redirection error causes the
command to exit with a non-zero status.
- If there is a command name left after expansion, execution proceeds as
- described below. Otherwise, the command exits. If one of the expan-
- sions contained a command substitution, the exit status of the command
- is the exit status of the last command substitution performed. If
+ If there is a command name left after expansion, execution proceeds as
+ described below. Otherwise, the command exits. If one of the expan-
+ sions contained a command substitution, the exit status of the command
+ is the exit status of the last command substitution performed. If
there were no command substitutions, the command exits with a status of
zero.
C\bCO\bOM\bMM\bMA\bAN\bND\bD E\bEX\bXE\bEC\bCU\bUT\bTI\bIO\bON\bN
- After a command has been split into words, if it results in a simple
- command and an optional list of arguments, the following actions are
+ After a command has been split into words, if it results in a simple
+ command and an optional list of arguments, the following actions are
taken.
- If the command name contains no slashes, the shell attempts to locate
- it. If there exists a shell function by that name, that function is
- invoked as described above in F\bFU\bUN\bNC\bCT\bTI\bIO\bON\bNS\bS. If the name does not match a
- function, the shell searches for it in the list of shell builtins. If
+ If the command name contains no slashes, the shell attempts to locate
+ it. If there exists a shell function by that name, that function is
+ invoked as described above in F\bFU\bUN\bNC\bCT\bTI\bIO\bON\bNS\bS. If the name does not match a
+ function, the shell searches for it in the list of shell builtins. If
a match is found, that builtin is invoked.
- If the name is neither a shell function nor a builtin, and contains no
- slashes, b\bba\bas\bsh\bh searches each element of the P\bPA\bAT\bTH\bH for a directory con-
+ If the name is neither a shell function nor a builtin, and contains no
+ slashes, b\bba\bas\bsh\bh searches each element of the P\bPA\bAT\bTH\bH for a directory con-
taining an executable file by that name. B\bBa\bas\bsh\bh uses a hash table to re-
- member the full pathnames of executable files (see h\bha\bas\bsh\bh under S\bSH\bHE\bEL\bLL\bL
- B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below). A full search of the directories in P\bPA\bAT\bTH\bH is
- performed only if the command is not found in the hash table. If the
+ member the full pathnames of executable files (see h\bha\bas\bsh\bh under S\bSH\bHE\bEL\bLL\bL
+ B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below). A full search of the directories in P\bPA\bAT\bTH\bH is
+ performed only if the command is not found in the hash table. If the
search is unsuccessful, the shell searches for a defined shell function
named c\bco\bom\bmm\bma\ban\bnd\bd_\b_n\bno\bot\bt_\b_f\bfo\bou\bun\bnd\bd_\b_h\bha\ban\bnd\bdl\ble\be. If that function exists, it is invoked
- in a separate execution environment with the original command and the
- original command's arguments as its arguments, and the function's exit
- status becomes the exit status of that subshell. If that function is
+ in a separate execution environment with the original command and the
+ original command's arguments as its arguments, and the function's exit
+ status becomes the exit status of that subshell. If that function is
not defined, the shell prints an error message and returns an exit sta-
tus of 127.
- If the search is successful, or if the command name contains one or
+ If the search is successful, or if the command name contains one or
more slashes, the shell executes the named program in a separate execu-
tion environment. Argument 0 is set to the name given, and the remain-
ing arguments to the command are set to the arguments given, if any.
- If this execution fails because the file is not in executable format,
- and the file is not a directory, it is assumed to be a _\bs_\bh_\be_\bl_\bl _\bs_\bc_\br_\bi_\bp_\bt, a
+ If this execution fails because the file is not in executable format,
+ and the file is not a directory, it is assumed to be a _\bs_\bh_\be_\bl_\bl _\bs_\bc_\br_\bi_\bp_\bt, a
file containing shell commands, and the shell creates a new instance of
- itself to execute it. This subshell reinitializes itself, so that the
+ itself to execute it. This subshell reinitializes itself, so that the
effect is as if a new shell had been invoked to handle the script, with
- the exception that the locations of commands remembered by the parent
- (see h\bha\bas\bsh\bh below under S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS) are retained by the
+ the exception that the locations of commands remembered by the parent
+ (see h\bha\bas\bsh\bh below under S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS) are retained by the
child.
- If the program is a file beginning with #\b#!\b!, the remainder of the first
- line specifies an interpreter for the program. The shell executes the
+ If the program is a file beginning with #\b#!\b!, the remainder of the first
+ line specifies an interpreter for the program. The shell executes the
specified interpreter on operating systems that do not handle this exe-
cutable format themselves. The arguments to the interpreter consist of
- a single optional argument following the interpreter name on the first
- line of the program, followed by the name of the program, followed by
+ a single optional argument following the interpreter name on the first
+ line of the program, followed by the name of the program, followed by
the command arguments, if any.
C\bCO\bOM\bMM\bMA\bAN\bND\bD E\bEX\bXE\bEC\bCU\bUT\bTI\bIO\bON\bN E\bEN\bNV\bVI\bIR\bRO\bON\bNM\bME\bEN\bNT\bT
- The shell has an _\be_\bx_\be_\bc_\bu_\bt_\bi_\bo_\bn _\be_\bn_\bv_\bi_\br_\bo_\bn_\bm_\be_\bn_\bt, which consists of the follow-
+ The shell has an _\be_\bx_\be_\bc_\bu_\bt_\bi_\bo_\bn _\be_\bn_\bv_\bi_\br_\bo_\bn_\bm_\be_\bn_\bt, which consists of the follow-
ing:
- +\bo open files inherited by the shell at invocation, as modified by
+ +\bo open files inherited by the shell at invocation, as modified by
redirections supplied to the e\bex\bxe\bec\bc builtin
- +\bo the current working directory as set by c\bcd\bd, p\bpu\bus\bsh\bhd\bd, or p\bpo\bop\bpd\bd, or
+ +\bo the current working directory as set by c\bcd\bd, p\bpu\bus\bsh\bhd\bd, or p\bpo\bop\bpd\bd, or
inherited by the shell at invocation
- +\bo the file creation mode mask as set by u\bum\bma\bas\bsk\bk or inherited from
+ +\bo the file creation mode mask as set by u\bum\bma\bas\bsk\bk or inherited from
the shell's parent
+\bo current traps set by t\btr\bra\bap\bp
+\bo shell parameters that are set by variable assignment or with s\bse\bet\bt
or inherited from the shell's parent in the environment
- +\bo shell functions defined during execution or inherited from the
+ +\bo shell functions defined during execution or inherited from the
shell's parent in the environment
- +\bo options enabled at invocation (either by default or with com-
+ +\bo options enabled at invocation (either by default or with com-
mand-line arguments) or by s\bse\bet\bt
+\bo options enabled by s\bsh\bho\bop\bpt\bt
+\bo shell aliases defined with a\bal\bli\bia\bas\bs
- +\bo various process IDs, including those of background jobs, the
+ +\bo various process IDs, including those of background jobs, the
value of $\b$$\b$, and the value of P\bPP\bPI\bID\bD
- When a simple command other than a builtin or shell function is to be
- executed, it is invoked in a separate execution environment that con-
- sists of the following. Unless otherwise noted, the values are inher-
+ When a simple command other than a builtin or shell function is to be
+ executed, it is invoked in a separate execution environment that con-
+ sists of the following. Unless otherwise noted, the values are inher-
ited from the shell.
- +\bo the shell's open files, plus any modifications and additions
+ +\bo the shell's open files, plus any modifications and additions
specified by redirections to the command
+\bo the current working directory
+\bo the file creation mode mask
- +\bo shell variables and functions marked for export, along with
+ +\bo shell variables and functions marked for export, along with
variables exported for the command, passed in the environment
+\bo traps caught by the shell are reset to the values inherited from
the shell's parent, and traps ignored by the shell are ignored
- A command invoked in this separate environment cannot affect the
+ A command invoked in this separate environment cannot affect the
shell's execution environment.
A _\bs_\bu_\bb_\bs_\bh_\be_\bl_\bl is a copy of the shell process.
- Command substitution, commands grouped with parentheses, and asynchro-
+ Command substitution, commands grouped with parentheses, and asynchro-
nous commands are invoked in a subshell environment that is a duplicate
of the shell environment, except that traps caught by the shell are re-
- set to the values that the shell inherited from its parent at invoca-
+ set to the values that the shell inherited from its parent at invoca-
tion. Builtin commands that are invoked as part of a pipeline are also
executed in a subshell environment. Changes made to the subshell envi-
ronment cannot affect the shell's execution environment.
Subshells spawned to execute command substitutions inherit the value of
- the -\b-e\be option from the parent shell. When not in _\bp_\bo_\bs_\bi_\bx _\bm_\bo_\bd_\be, b\bba\bas\bsh\bh
+ the -\b-e\be option from the parent shell. When not in _\bp_\bo_\bs_\bi_\bx _\bm_\bo_\bd_\be, b\bba\bas\bsh\bh
clears the -\b-e\be option in such subshells.
- If a command is followed by a &\b& and job control is not active, the de-
+ If a command is followed by a &\b& and job control is not active, the de-
fault standard input for the command is the empty file _\b/_\bd_\be_\bv_\b/_\bn_\bu_\bl_\bl. Oth-
- erwise, the invoked command inherits the file descriptors of the call-
+ erwise, the invoked command inherits the file descriptors of the call-
ing shell as modified by redirections.
E\bEN\bNV\bVI\bIR\bRO\bON\bNM\bME\bEN\bNT\bT
- When a program is invoked it is given an array of strings called the
+ When a program is invoked it is given an array of strings called the
_\be_\bn_\bv_\bi_\br_\bo_\bn_\bm_\be_\bn_\bt. This is a list of _\bn_\ba_\bm_\be-_\bv_\ba_\bl_\bu_\be pairs, of the form
_\bn_\ba_\bm_\be=_\bv_\ba_\bl_\bu_\be.
- The shell provides several ways to manipulate the environment. On in-
- vocation, the shell scans its own environment and creates a parameter
- for each name found, automatically marking it for _\be_\bx_\bp_\bo_\br_\bt to child pro-
+ The shell provides several ways to manipulate the environment. On in-
+ vocation, the shell scans its own environment and creates a parameter
+ for each name found, automatically marking it for _\be_\bx_\bp_\bo_\br_\bt to child pro-
cesses. Executed commands inherit the environment. The e\bex\bxp\bpo\bor\brt\bt and d\bde\be-\b-
- c\bcl\bla\bar\bre\be -\b-x\bx commands allow parameters and functions to be added to and
+ c\bcl\bla\bar\bre\be -\b-x\bx commands allow parameters and functions to be added to and
deleted from the environment. If the value of a parameter in the envi-
ronment is modified, the new value becomes part of the environment, re-
- placing the old. The environment inherited by any executed command
- consists of the shell's initial environment, whose values may be modi-
- fied in the shell, less any pairs removed by the u\bun\bns\bse\bet\bt command, plus
+ placing the old. The environment inherited by any executed command
+ consists of the shell's initial environment, whose values may be modi-
+ fied in the shell, less any pairs removed by the u\bun\bns\bse\bet\bt command, plus
any additions via the e\bex\bxp\bpo\bor\brt\bt and d\bde\bec\bcl\bla\bar\bre\be -\b-x\bx commands.
- The environment for any _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd or function may be augmented
- temporarily by prefixing it with parameter assignments, as described
+ The environment for any _\bs_\bi_\bm_\bp_\bl_\be _\bc_\bo_\bm_\bm_\ba_\bn_\bd or function may be augmented
+ temporarily by prefixing it with parameter assignments, as described
above in P\bPA\bAR\bRA\bAM\bME\bET\bTE\bER\bRS\bS. These assignment statements affect only the envi-
ronment seen by that command.
- If the -\b-k\bk option is set (see the s\bse\bet\bt builtin command below), then _\ba_\bl_\bl
- parameter assignments are placed in the environment for a command, not
+ If the -\b-k\bk option is set (see the s\bse\bet\bt builtin command below), then _\ba_\bl_\bl
+ parameter assignments are placed in the environment for a command, not
just those that precede the command name.
- When b\bba\bas\bsh\bh invokes an external command, the variable _\b_ is set to the
+ When b\bba\bas\bsh\bh invokes an external command, the variable _\b_ is set to the
full filename of the command and passed to that command in its environ-
ment.
E\bEX\bXI\bIT\bT S\bST\bTA\bAT\bTU\bUS\bS
- The exit status of an executed command is the value returned by the
+ The exit status of an executed command is the value returned by the
_\bw_\ba_\bi_\bt_\bp_\bi_\bd system call or equivalent function. Exit statuses fall between
- 0 and 255, though, as explained below, the shell may use values above
+ 0 and 255, though, as explained below, the shell may use values above
125 specially. Exit statuses from shell builtins and compound commands
are also limited to this range. Under certain circumstances, the shell
will use special values to indicate specific failure modes.
For the shell's purposes, a command which exits with a zero exit status
- has succeeded. An exit status of zero indicates success. A non-zero
- exit status indicates failure. When a command terminates on a fatal
+ has succeeded. An exit status of zero indicates success. A non-zero
+ exit status indicates failure. When a command terminates on a fatal
signal _\bN, b\bba\bas\bsh\bh uses the value of 128+_\bN as the exit status.
- If a command is not found, the child process created to execute it re-
- turns a status of 127. If a command is found but is not executable,
+ If a command is not found, the child process created to execute it re-
+ turns a status of 127. If a command is found but is not executable,
the return status is 126.
If a command fails because of an error during expansion or redirection,
the exit status is greater than zero.
- Shell builtin commands return a status of 0 (_\bt_\br_\bu_\be) if successful, and
- non-zero (_\bf_\ba_\bl_\bs_\be) if an error occurs while they execute. All builtins
- return an exit status of 2 to indicate incorrect usage, generally in-
+ Shell builtin commands return a status of 0 (_\bt_\br_\bu_\be) if successful, and
+ non-zero (_\bf_\ba_\bl_\bs_\be) if an error occurs while they execute. All builtins
+ return an exit status of 2 to indicate incorrect usage, generally in-
valid options or missing arguments.
The exit status of the last command is available in the special parame-
ter $?.
- B\bBa\bas\bsh\bh itself returns the exit status of the last command executed, un-
- less a syntax error occurs, in which case it exits with a non-zero
+ B\bBa\bas\bsh\bh itself returns the exit status of the last command executed, un-
+ less a syntax error occurs, in which case it exits with a non-zero
value. See also the e\bex\bxi\bit\bt builtin command below.
S\bSI\bIG\bGN\bNA\bAL\bLS\bS
- When b\bba\bas\bsh\bh is interactive, in the absence of any traps, it ignores
+ When b\bba\bas\bsh\bh is interactive, in the absence of any traps, it ignores
S\bSI\bIG\bGT\bTE\bER\bRM\bM (so that k\bki\bil\bll\bl 0\b0 does not kill an interactive shell), and S\bSI\bIG\bGI\bIN\bNT\bT
- is caught and handled (so that the w\bwa\bai\bit\bt builtin is interruptible). In
+ is caught and handled (so that the w\bwa\bai\bit\bt builtin is interruptible). In
all cases, b\bba\bas\bsh\bh ignores S\bSI\bIG\bGQ\bQU\bUI\bIT\bT. If job control is in effect, b\bba\bas\bsh\bh ig-
nores S\bSI\bIG\bGT\bTT\bTI\bIN\bN, S\bSI\bIG\bGT\bTT\bTO\bOU\bU, and S\bSI\bIG\bGT\bTS\bST\bTP\bP.
Non-builtin commands run by b\bba\bas\bsh\bh have signal handlers set to the values
inherited by the shell from its parent. When job control is not in ef-
- fect, asynchronous commands ignore S\bSI\bIG\bGI\bIN\bNT\bT and S\bSI\bIG\bGQ\bQU\bUI\bIT\bT in addition to
- these inherited handlers. Commands run as a result of command substi-
+ fect, asynchronous commands ignore S\bSI\bIG\bGI\bIN\bNT\bT and S\bSI\bIG\bGQ\bQU\bUI\bIT\bT in addition to
+ these inherited handlers. Commands run as a result of command substi-
tution ignore the keyboard-generated job control signals S\bSI\bIG\bGT\bTT\bTI\bIN\bN, S\bSI\bIG\bGT\bT-\b-
T\bTO\bOU\bU, and S\bSI\bIG\bGT\bTS\bST\bTP\bP.
- The shell exits by default upon receipt of a S\bSI\bIG\bGH\bHU\bUP\bP. Before exiting,
- an interactive shell resends the S\bSI\bIG\bGH\bHU\bUP\bP to all jobs, running or
+ The shell exits by default upon receipt of a S\bSI\bIG\bGH\bHU\bUP\bP. Before exiting,
+ an interactive shell resends the S\bSI\bIG\bGH\bHU\bUP\bP to all jobs, running or
stopped. Stopped jobs are sent S\bSI\bIG\bGC\bCO\bON\bNT\bT to ensure that they receive the
- S\bSI\bIG\bGH\bHU\bUP\bP. To prevent the shell from sending the signal to a particular
- job, it should be removed from the jobs table with the d\bdi\bis\bso\bow\bwn\bn builtin
- (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below) or marked to not receive S\bSI\bIG\bGH\bHU\bUP\bP us-
+ S\bSI\bIG\bGH\bHU\bUP\bP. To prevent the shell from sending the signal to a particular
+ job, it should be removed from the jobs table with the d\bdi\bis\bso\bow\bwn\bn builtin
+ (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below) or marked to not receive S\bSI\bIG\bGH\bHU\bUP\bP us-
ing d\bdi\bis\bso\bow\bwn\bn -\b-h\bh.
- If the h\bhu\bup\bpo\bon\bne\bex\bxi\bit\bt shell option has been set with s\bsh\bho\bop\bpt\bt, b\bba\bas\bsh\bh sends a
+ If the h\bhu\bup\bpo\bon\bne\bex\bxi\bit\bt shell option has been set with s\bsh\bho\bop\bpt\bt, b\bba\bas\bsh\bh sends a
S\bSI\bIG\bGH\bHU\bUP\bP to all jobs when an interactive login shell exits.
- If b\bba\bas\bsh\bh is waiting for a command to complete and receives a signal for
+ If b\bba\bas\bsh\bh is waiting for a command to complete and receives a signal for
which a trap has been set, the trap will not be executed until the com-
- mand completes. When b\bba\bas\bsh\bh is waiting for an asynchronous command via
- the w\bwa\bai\bit\bt builtin, the reception of a signal for which a trap has been
+ mand completes. When b\bba\bas\bsh\bh is waiting for an asynchronous command via
+ the w\bwa\bai\bit\bt builtin, the reception of a signal for which a trap has been
set will cause the w\bwa\bai\bit\bt builtin to return immediately with an exit sta-
tus greater than 128, immediately after which the trap is executed.
- When job control is not enabled, and b\bba\bas\bsh\bh is waiting for a foreground
+ When job control is not enabled, and b\bba\bas\bsh\bh is waiting for a foreground
command to complete, the shell receives keyboard-generated signals such
- as S\bSI\bIG\bGI\bIN\bNT\bT (usually generated by ^\b^C\bC) that users commonly intend to send
+ as S\bSI\bIG\bGI\bIN\bNT\bT (usually generated by ^\b^C\bC) that users commonly intend to send
to that command. This happens because the shell and the command are in
the same process group as the terminal, and ^\b^C\bC sends S\bSI\bIG\bGI\bIN\bNT\bT to all pro-
cesses in that process group.
- When b\bba\bas\bsh\bh is running without job control enabled and receives S\bSI\bIG\bGI\bIN\bNT\bT
- while waiting for a foreground command, it waits until that foreground
+ When b\bba\bas\bsh\bh is running without job control enabled and receives S\bSI\bIG\bGI\bIN\bNT\bT
+ while waiting for a foreground command, it waits until that foreground
command terminates and then decides what to do about the S\bSI\bIG\bGI\bIN\bNT\bT:
1. If the command terminates due to the S\bSI\bIG\bGI\bIN\bNT\bT, b\bba\bas\bsh\bh concludes that
- the user meant to end the entire script, and acts on the S\bSI\bIG\bGI\bIN\bNT\bT
+ the user meant to end the entire script, and acts on the S\bSI\bIG\bGI\bIN\bNT\bT
(e.g., by running a S\bSI\bIG\bGI\bIN\bNT\bT trap or exiting itself);
- 2. If the command does not terminate due to S\bSI\bIG\bGI\bIN\bNT\bT, the program
- handled the S\bSI\bIG\bGI\bIN\bNT\bT itself and did not treat it as a fatal sig-
- nal. In that case, b\bba\bas\bsh\bh does not treat S\bSI\bIG\bGI\bIN\bNT\bT as a fatal sig-
- nal, either, instead assuming that the S\bSI\bIG\bGI\bIN\bNT\bT was used as part
- of the program's normal operation (e.g., emacs uses it to abort
+ 2. If the command does not terminate due to S\bSI\bIG\bGI\bIN\bNT\bT, the program
+ handled the S\bSI\bIG\bGI\bIN\bNT\bT itself and did not treat it as a fatal sig-
+ nal. In that case, b\bba\bas\bsh\bh does not treat S\bSI\bIG\bGI\bIN\bNT\bT as a fatal sig-
+ nal, either, instead assuming that the S\bSI\bIG\bGI\bIN\bNT\bT was used as part
+ of the program's normal operation (e.g., emacs uses it to abort
editing commands) or deliberately discarded. However, b\bba\bas\bsh\bh will
- run any trap set on S\bSI\bIG\bGI\bIN\bNT\bT, as it does with any other trapped
- signal it receives while it is waiting for the foreground com-
+ run any trap set on S\bSI\bIG\bGI\bIN\bNT\bT, as it does with any other trapped
+ signal it receives while it is waiting for the foreground com-
mand to complete, for compatibility.
J\bJO\bOB\bB C\bCO\bON\bNT\bTR\bRO\bOL\bL
_\bJ_\bo_\bb _\bc_\bo_\bn_\bt_\br_\bo_\bl refers to the ability to selectively stop (_\bs_\bu_\bs_\bp_\be_\bn_\bd) the ex-
- ecution of processes and continue (_\br_\be_\bs_\bu_\bm_\be) their execution at a later
- point. A user typically employs this facility via an interactive in-
- terface supplied jointly by the operating system kernel's terminal
+ ecution of processes and continue (_\br_\be_\bs_\bu_\bm_\be) their execution at a later
+ point. A user typically employs this facility via an interactive in-
+ terface supplied jointly by the operating system kernel's terminal
driver and b\bba\bas\bsh\bh.
- The shell associates a _\bj_\bo_\bb with each pipeline. It keeps a table of
- currently executing jobs, which may be listed with the j\bjo\bob\bbs\bs command.
- When b\bba\bas\bsh\bh starts a job asynchronously (in the _\bb_\ba_\bc_\bk_\bg_\br_\bo_\bu_\bn_\bd), it prints a
+ The shell associates a _\bj_\bo_\bb with each pipeline. It keeps a table of
+ currently executing jobs, which may be listed with the j\bjo\bob\bbs\bs command.
+ When b\bba\bas\bsh\bh starts a job asynchronously (in the _\bb_\ba_\bc_\bk_\bg_\br_\bo_\bu_\bn_\bd), it prints a
line that looks like:
[1] 25647
indicating that this job is job number 1 and that the process ID of the
last process in the pipeline associated with this job is 25647. All of
- the processes in a single pipeline are members of the same job. B\bBa\bas\bsh\bh
+ the processes in a single pipeline are members of the same job. B\bBa\bas\bsh\bh
uses the _\bj_\bo_\bb abstraction as the basis for job control.
- To facilitate the implementation of the user interface to job control,
+ To facilitate the implementation of the user interface to job control,
the operating system maintains the notion of a _\bc_\bu_\br_\br_\be_\bn_\bt _\bt_\be_\br_\bm_\bi_\bn_\ba_\bl _\bp_\br_\bo_\bc_\be_\bs_\bs
_\bg_\br_\bo_\bu_\bp _\bI_\bD. Members of this process group (processes whose process group
ID is equal to the current terminal process group ID) receive keyboard-
- generated signals such as S\bSI\bIG\bGI\bIN\bNT\bT. These processes are said to be in
- the _\bf_\bo_\br_\be_\bg_\br_\bo_\bu_\bn_\bd. _\bB_\ba_\bc_\bk_\bg_\br_\bo_\bu_\bn_\bd processes are those whose process group ID
+ generated signals such as S\bSI\bIG\bGI\bIN\bNT\bT. These processes are said to be in
+ the _\bf_\bo_\br_\be_\bg_\br_\bo_\bu_\bn_\bd. _\bB_\ba_\bc_\bk_\bg_\br_\bo_\bu_\bn_\bd processes are those whose process group ID
differs from the terminal's; such processes are immune to keyboard-gen-
erated signals. Only foreground processes are allowed to read from or,
- if the user so specifies with stty tostop, write to the terminal.
- Background processes which attempt to read from (write to when stty
- tostop is in effect) the terminal are sent a S\bSI\bIG\bGT\bTT\bTI\bIN\bN (\b(S\bSI\bIG\bGT\bTT\bTO\bOU\bU)\b) signal
- by the kernel's terminal driver, which, unless caught, suspends the
+ if the user so specifies with stty tostop, write to the terminal.
+ Background processes which attempt to read from (write to when stty
+ tostop is in effect) the terminal are sent a S\bSI\bIG\bGT\bTT\bTI\bIN\bN (\b(S\bSI\bIG\bGT\bTT\bTO\bOU\bU)\b) signal
+ by the kernel's terminal driver, which, unless caught, suspends the
process.
- If the operating system on which b\bba\bas\bsh\bh is running supports job control,
+ If the operating system on which b\bba\bas\bsh\bh is running supports job control,
b\bba\bas\bsh\bh contains facilities to use it. Typing the _\bs_\bu_\bs_\bp_\be_\bn_\bd character (typ-
ically ^\b^Z\bZ, Control-Z) while a process is running causes that process to
- be stopped and returns control to b\bba\bas\bsh\bh. Typing the _\bd_\be_\bl_\ba_\by_\be_\bd _\bs_\bu_\bs_\bp_\be_\bn_\bd
- character (typically ^\b^Y\bY, Control-Y) causes the process to be stopped
+ be stopped and returns control to b\bba\bas\bsh\bh. Typing the _\bd_\be_\bl_\ba_\by_\be_\bd _\bs_\bu_\bs_\bp_\be_\bn_\bd
+ character (typically ^\b^Y\bY, Control-Y) causes the process to be stopped
when it attempts to read input from the terminal, and control to be re-
- turned to b\bba\bas\bsh\bh. The user may then manipulate the state of this job,
- using the b\bbg\bg command to continue it in the background, the f\bfg\bg command
+ turned to b\bba\bas\bsh\bh. The user may then manipulate the state of this job,
+ using the b\bbg\bg command to continue it in the background, the f\bfg\bg command
to continue it in the foreground, or the k\bki\bil\bll\bl command to kill it. A ^\b^Z\bZ
takes effect immediately, and has the additional side effect of causing
pending output and typeahead to be discarded.
There are a number of ways to refer to a job in the shell. The charac-
- ter %\b% introduces a job specification (_\bj_\bo_\bb_\bs_\bp_\be_\bc). Job number _\bn may be
+ ter %\b% introduces a job specification (_\bj_\bo_\bb_\bs_\bp_\be_\bc). Job number _\bn may be
referred to as %\b%n\bn. A job may also be referred to using a prefix of the
name used to start it, or using a substring that appears in its command
- line. For example, %\b%c\bce\be refers to a stopped job whose command name be-
- gins with c\bce\be. If a prefix matches more than one job, b\bba\bas\bsh\bh reports an
+ line. For example, %\b%c\bce\be refers to a stopped job whose command name be-
+ gins with c\bce\be. If a prefix matches more than one job, b\bba\bas\bsh\bh reports an
error. Using %\b%?\b?c\bce\be, on the other hand, refers to any job containing the
- string c\bce\be in its command line. If the substring matches more than one
+ string c\bce\be in its command line. If the substring matches more than one
job, b\bba\bas\bsh\bh reports an error. The symbols %\b%%\b% and %\b%+\b+ refer to the shell's
- notion of the _\bc_\bu_\br_\br_\be_\bn_\bt _\bj_\bo_\bb, which is the last job stopped while it was
- in the foreground or started in the background. The _\bp_\br_\be_\bv_\bi_\bo_\bu_\bs _\bj_\bo_\bb may
- be referenced using %\b%-\b-. If there is only a single job, %\b%+\b+ and %\b%-\b- can
+ notion of the _\bc_\bu_\br_\br_\be_\bn_\bt _\bj_\bo_\bb, which is the last job stopped while it was
+ in the foreground or started in the background. The _\bp_\br_\be_\bv_\bi_\bo_\bu_\bs _\bj_\bo_\bb may
+ be referenced using %\b%-\b-. If there is only a single job, %\b%+\b+ and %\b%-\b- can
both be used to refer to that job. In output pertaining to jobs (e.g.,
the output of the j\bjo\bob\bbs\bs command), the current job is always flagged with
- a +\b+, and the previous job with a -\b-. A single % (with no accompanying
+ a +\b+, and the previous job with a -\b-. A single % (with no accompanying
job specification) also refers to the current job.
- Simply naming a job can be used to bring it into the foreground: %\b%1\b1 is
- a synonym for `\b``\b`f\bfg\bg %\b%1\b1'\b''\b', bringing job 1 from the background into the
- foreground. Similarly, `\b``\b`%\b%1\b1 &\b&'\b''\b' resumes job 1 in the background,
+ Simply naming a job can be used to bring it into the foreground: %\b%1\b1 is
+ a synonym for `\b``\b`f\bfg\bg %\b%1\b1'\b''\b', bringing job 1 from the background into the
+ foreground. Similarly, `\b``\b`%\b%1\b1 &\b&'\b''\b' resumes job 1 in the background,
equivalent to `\b``\b`b\bbg\bg %\b%1\b1'\b''\b'.
- The shell learns immediately whenever a job changes state. Normally,
+ The shell learns immediately whenever a job changes state. Normally,
b\bba\bas\bsh\bh waits until it is about to print a prompt before reporting changes
- in a job's status so as to not interrupt any other output. If the -\b-b\bb
+ in a job's status so as to not interrupt any other output. If the -\b-b\bb
option to the s\bse\bet\bt builtin command is enabled, b\bba\bas\bsh\bh reports such changes
- immediately. Any trap on S\bSI\bIG\bGC\bCH\bHL\bLD\bD is executed for each child that ex-
+ immediately. Any trap on S\bSI\bIG\bGC\bCH\bHL\bLD\bD is executed for each child that ex-
its.
- If an attempt to exit b\bba\bas\bsh\bh is made while jobs are stopped (or, if the
- c\bch\bhe\bec\bck\bkj\bjo\bob\bbs\bs shell option has been enabled using the s\bsh\bho\bop\bpt\bt builtin, run-
+ If an attempt to exit b\bba\bas\bsh\bh is made while jobs are stopped (or, if the
+ c\bch\bhe\bec\bck\bkj\bjo\bob\bbs\bs shell option has been enabled using the s\bsh\bho\bop\bpt\bt builtin, run-
ning), the shell prints a warning message, and, if the c\bch\bhe\bec\bck\bkj\bjo\bob\bbs\bs option
- is enabled, lists the jobs and their statuses. The j\bjo\bob\bbs\bs command may
- then be used to inspect their status. If a second attempt to exit is
- made without an intervening command, the shell does not print another
+ is enabled, lists the jobs and their statuses. The j\bjo\bob\bbs\bs command may
+ then be used to inspect their status. If a second attempt to exit is
+ made without an intervening command, the shell does not print another
warning, and any stopped jobs are terminated.
- When the shell is waiting for a job or process using the w\bwa\bai\bit\bt builtin,
- and job control is enabled, w\bwa\bai\bit\bt will return when the job changes
- state. The -\b-f\bf option causes w\bwa\bai\bit\bt to wait until the job or process ter-
+ When the shell is waiting for a job or process using the w\bwa\bai\bit\bt builtin,
+ and job control is enabled, w\bwa\bai\bit\bt will return when the job changes
+ state. The -\b-f\bf option causes w\bwa\bai\bit\bt to wait until the job or process ter-
minates before returning.
P\bPR\bRO\bOM\bMP\bPT\bTI\bIN\bNG\bG
When executing interactively, b\bba\bas\bsh\bh displays the primary prompt P\bPS\bS1\b1 when
- it is ready to read a command, and the secondary prompt P\bPS\bS2\b2 when it
- needs more input to complete a command. B\bBa\bas\bsh\bh displays P\bPS\bS0\b0 after it
- reads a command but before executing it. B\bBa\bas\bsh\bh displays P\bPS\bS4\b4 as de-
- scribed above before tracing each command when the -\b-x\bx option is en-
- abled. B\bBa\bas\bsh\bh allows these prompt strings to be customized by inserting
- a number of backslash-escaped special characters that are decoded as
+ it is ready to read a command, and the secondary prompt P\bPS\bS2\b2 when it
+ needs more input to complete a command. B\bBa\bas\bsh\bh displays P\bPS\bS0\b0 after it
+ reads a command but before executing it. B\bBa\bas\bsh\bh displays P\bPS\bS4\b4 as de-
+ scribed above before tracing each command when the -\b-x\bx option is en-
+ abled. B\bBa\bas\bsh\bh allows these prompt strings to be customized by inserting
+ a number of backslash-escaped special characters that are decoded as
follows:
\\b\a\ba an ASCII bell character (07)
- \\b\d\bd the date in "Weekday Month Date" format (e.g., "Tue May
+ \\b\d\bd the date in "Weekday Month Date" format (e.g., "Tue May
26")
\\b\D\bD{\b{_\bf_\bo_\br_\bm_\ba_\bt}\b}
the _\bf_\bo_\br_\bm_\ba_\bt is passed to _\bs_\bt_\br_\bf_\bt_\bi_\bm_\be(3) and the result is in-
serted into the prompt string; an empty _\bf_\bo_\br_\bm_\ba_\bt results in
- a locale-specific time representation. The braces are
+ a locale-specific time representation. The braces are
required
\\b\e\be an ASCII escape character (033)
\\b\h\bh the hostname up to the first `.'
\\b\l\bl the basename of the shell's terminal device name
\\b\n\bn newline
\\b\r\br carriage return
- \\b\s\bs the name of the shell, the basename of $\b$0\b0 (the portion
+ \\b\s\bs the name of the shell, the basename of $\b$0\b0 (the portion
following the final slash)
\\b\t\bt the current time in 24-hour HH:MM:SS format
\\b\T\bT the current time in 12-hour HH:MM:SS format
\\b\u\bu the username of the current user
\\b\v\bv the version of b\bba\bas\bsh\bh (e.g., 2.00)
\\b\V\bV the release of b\bba\bas\bsh\bh, version + patch level (e.g., 2.00.0)
- \\b\w\bw the value of the P\bPW\bWD\bD shell variable ($\b$P\bPW\bWD\bD), with $\b$H\bHO\bOM\bME\bE
- abbreviated with a tilde (uses the value of the
+ \\b\w\bw the value of the P\bPW\bWD\bD shell variable ($\b$P\bPW\bWD\bD), with $\b$H\bHO\bOM\bME\bE
+ abbreviated with a tilde (uses the value of the
P\bPR\bRO\bOM\bMP\bPT\bT_\b_D\bDI\bIR\bRT\bTR\bRI\bIM\bM variable)
\\b\W\bW the basename of $\b$P\bPW\bWD\bD, with $\b$H\bHO\bOM\bME\bE abbreviated with a tilde
\\b\!\b! the history number of this command
\\b\$\b$ if the effective UID is 0, a #\b#, otherwise a $\b$
\\b\_\bn_\bn_\bn the character corresponding to the octal number _\bn_\bn_\bn
\\b\\\b\ a backslash
- \\b\[\b[ begin a sequence of non-printing characters, which could
- be used to embed a terminal control sequence into the
+ \\b\[\b[ begin a sequence of non-printing characters, which could
+ be used to embed a terminal control sequence into the
prompt
\\b\]\b] end a sequence of non-printing characters
- The command number and the history number are usually different: the
- history number of a command is its position in the history list, which
- may include commands restored from the history file (see H\bHI\bIS\bST\bTO\bOR\bRY\bY be-
- low), while the command number is the position in the sequence of com-
- mands executed during the current shell session. After the string is
- decoded, it is expanded via parameter expansion, command substitution,
- arithmetic expansion, and quote removal, subject to the value of the
+ The command number and the history number are usually different: the
+ history number of a command is its position in the history list, which
+ may include commands restored from the history file (see H\bHI\bIS\bST\bTO\bOR\bRY\bY be-
+ low), while the command number is the position in the sequence of com-
+ mands executed during the current shell session. After the string is
+ decoded, it is expanded via parameter expansion, command substitution,
+ arithmetic expansion, and quote removal, subject to the value of the
p\bpr\bro\bom\bmp\bpt\btv\bva\bar\brs\bs shell option (see the description of the s\bsh\bho\bop\bpt\bt command under
- S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below). This can have unwanted side effects if
- escaped portions of the string appear within command substitution or
+ S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below). This can have unwanted side effects if
+ escaped portions of the string appear within command substitution or
contain characters special to word expansion.
R\bRE\bEA\bAD\bDL\bLI\bIN\bNE\bE
- This is the library that handles reading input when using an interac-
+ This is the library that handles reading input when using an interac-
tive shell, unless the -\b--\b-n\bno\boe\bed\bdi\bit\bti\bin\bng\bg option is given at shell invocation.
Line editing is also used when using the -\b-e\be option to the r\bre\bea\bad\bd builtin.
By default, the line editing commands are similar to those of Emacs. A
vi-style line editing interface is also available. Line editing can be
- enabled at any time using the -\b-o\bo e\bem\bma\bac\bcs\bs or -\b-o\bo v\bvi\bi options to the s\bse\bet\bt
- builtin (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below). To turn off line editing
- after the shell is running, use the +\b+o\bo e\bem\bma\bac\bcs\bs or +\b+o\bo v\bvi\bi options to the
+ enabled at any time using the -\b-o\bo e\bem\bma\bac\bcs\bs or -\b-o\bo v\bvi\bi options to the s\bse\bet\bt
+ builtin (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below). To turn off line editing
+ after the shell is running, use the +\b+o\bo e\bem\bma\bac\bcs\bs or +\b+o\bo v\bvi\bi options to the
s\bse\bet\bt builtin.
R\bRe\bea\bad\bdl\bli\bin\bne\be N\bNo\bot\bta\bat\bti\bio\bon\bn
In this section, the Emacs-style notation is used to denote keystrokes.
- Control keys are denoted by C-_\bk_\be_\by, e.g., C-n means Control-N. Simi-
- larly, _\bm_\be_\bt_\ba keys are denoted by M-_\bk_\be_\by, so M-x means Meta-X. (On key-
- boards without a _\bm_\be_\bt_\ba key, M-_\bx means ESC _\bx, i.e., press the Escape key
+ Control keys are denoted by C-_\bk_\be_\by, e.g., C-n means Control-N. Simi-
+ larly, _\bm_\be_\bt_\ba keys are denoted by M-_\bk_\be_\by, so M-x means Meta-X. (On key-
+ boards without a _\bm_\be_\bt_\ba key, M-_\bx means ESC _\bx, i.e., press the Escape key
then the _\bx key. This makes ESC the _\bm_\be_\bt_\ba _\bp_\br_\be_\bf_\bi_\bx. The combination M-C-_\bx
- means ESC-Control-_\bx, or press the Escape key then hold the Control key
+ means ESC-Control-_\bx, or press the Escape key then hold the Control key
while pressing the _\bx key.)
Readline commands may be given numeric _\ba_\br_\bg_\bu_\bm_\be_\bn_\bt_\bs, which normally act as
- a repeat count. Sometimes, however, it is the sign of the argument
- that is significant. Passing a negative argument to a command that
- acts in the forward direction (e.g., k\bki\bil\bll\bl-\b-l\bli\bin\bne\be) causes that command to
- act in a backward direction. Commands whose behavior with arguments
+ a repeat count. Sometimes, however, it is the sign of the argument
+ that is significant. Passing a negative argument to a command that
+ acts in the forward direction (e.g., k\bki\bil\bll\bl-\b-l\bli\bin\bne\be) causes that command to
+ act in a backward direction. Commands whose behavior with arguments
deviates from this are noted below.
- When a command is described as _\bk_\bi_\bl_\bl_\bi_\bn_\bg text, the text deleted is saved
+ When a command is described as _\bk_\bi_\bl_\bl_\bi_\bn_\bg text, the text deleted is saved
for possible future retrieval (_\by_\ba_\bn_\bk_\bi_\bn_\bg). The killed text is saved in a
_\bk_\bi_\bl_\bl _\br_\bi_\bn_\bg. Consecutive kills cause the text to be accumulated into one
unit, which can be yanked all at once. Commands which do not kill text
separate the chunks of text on the kill ring.
R\bRe\bea\bad\bdl\bli\bin\bne\be I\bIn\bni\bit\bti\bia\bal\bli\biz\bza\bat\bti\bio\bon\bn
- Readline is customized by putting commands in an initialization file
- (the _\bi_\bn_\bp_\bu_\bt_\br_\bc file). The name of this file is taken from the value of
+ Readline is customized by putting commands in an initialization file
+ (the _\bi_\bn_\bp_\bu_\bt_\br_\bc file). The name of this file is taken from the value of
the I\bIN\bNP\bPU\bUT\bTR\bRC\bC variable. If that variable is unset, the default is _\b~_\b/_\b._\bi_\bn_\b-
- _\bp_\bu_\bt_\br_\bc. If that file does not exist or cannot be read, the ultimate
- default is _\b/_\be_\bt_\bc_\b/_\bi_\bn_\bp_\bu_\bt_\br_\bc. When a program which uses the readline li-
- brary starts up, the initialization file is read, and the key bindings
- and variables are set. There are only a few basic constructs allowed
- in the readline initialization file. Blank lines are ignored. Lines
- beginning with a #\b# are comments. Lines beginning with a $\b$ indicate
- conditional constructs. Other lines denote key bindings and variable
+ _\bp_\bu_\bt_\br_\bc. If that file does not exist or cannot be read, the ultimate
+ default is _\b/_\be_\bt_\bc_\b/_\bi_\bn_\bp_\bu_\bt_\br_\bc. When a program which uses the readline li-
+ brary starts up, the initialization file is read, and the key bindings
+ and variables are set. There are only a few basic constructs allowed
+ in the readline initialization file. Blank lines are ignored. Lines
+ beginning with a #\b# are comments. Lines beginning with a $\b$ indicate
+ conditional constructs. Other lines denote key bindings and variable
settings.
- The default key-bindings may be changed with an _\bi_\bn_\bp_\bu_\bt_\br_\bc file. Other
+ The default key-bindings may be changed with an _\bi_\bn_\bp_\bu_\bt_\br_\bc file. Other
programs that use this library may add their own commands and bindings.
For example, placing
M-Control-u: universal-argument
or
C-Meta-u: universal-argument
- into the _\bi_\bn_\bp_\bu_\bt_\br_\bc would make M-C-u execute the readline command _\bu_\bn_\bi_\bv_\be_\br_\b-
+ into the _\bi_\bn_\bp_\bu_\bt_\br_\bc would make M-C-u execute the readline command _\bu_\bn_\bi_\bv_\be_\br_\b-
_\bs_\ba_\bl_\b-_\ba_\br_\bg_\bu_\bm_\be_\bn_\bt.
- The following symbolic character names are recognized: _\bR_\bU_\bB_\bO_\bU_\bT, _\bD_\bE_\bL,
+ The following symbolic character names are recognized: _\bR_\bU_\bB_\bO_\bU_\bT, _\bD_\bE_\bL,
_\bE_\bS_\bC, _\bL_\bF_\bD, _\bN_\bE_\bW_\bL_\bI_\bN_\bE, _\bR_\bE_\bT, _\bR_\bE_\bT_\bU_\bR_\bN, _\bS_\bP_\bC, _\bS_\bP_\bA_\bC_\bE, and _\bT_\bA_\bB.
- In addition to command names, readline allows keys to be bound to a
+ In addition to command names, readline allows keys to be bound to a
string that is inserted when the key is pressed (a _\bm_\ba_\bc_\br_\bo).
R\bRe\bea\bad\bdl\bli\bin\bne\be K\bKe\bey\by B\bBi\bin\bnd\bdi\bin\bng\bgs\bs
- The syntax for controlling key bindings in the _\bi_\bn_\bp_\bu_\bt_\br_\bc file is simple.
- All that is required is the name of the command or the text of a macro
+ The syntax for controlling key bindings in the _\bi_\bn_\bp_\bu_\bt_\br_\bc file is simple.
+ All that is required is the name of the command or the text of a macro
and a key sequence to which it should be bound. The name may be speci-
fied in one of two ways: as a symbolic key name, possibly with _\bM_\be_\bt_\ba_\b- or
_\bC_\bo_\bn_\bt_\br_\bo_\bl_\b- prefixes, or as a key sequence.
Meta-Rubout: backward-kill-word
Control-o: "> output"
- In the above example, _\bC_\b-_\bu is bound to the function u\bun\bni\biv\bve\ber\brs\bsa\bal\bl-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt,
- _\bM_\b-_\bD_\bE_\bL is bound to the function b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-k\bki\bil\bll\bl-\b-w\bwo\bor\brd\bd, and _\bC_\b-_\bo is bound to
- run the macro expressed on the right hand side (that is, to insert the
+ In the above example, _\bC_\b-_\bu is bound to the function u\bun\bni\biv\bve\ber\brs\bsa\bal\bl-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt,
+ _\bM_\b-_\bD_\bE_\bL is bound to the function b\bba\bac\bck\bkw\bwa\bar\brd\bd-\b-k\bki\bil\bll\bl-\b-w\bwo\bor\brd\bd, and _\bC_\b-_\bo is bound to
+ run the macro expressed on the right hand side (that is, to insert the
text ``> output'' into the line).
- In the second form, "\b"k\bke\bey\bys\bse\beq\bq"\b":_\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be or _\bm_\ba_\bc_\br_\bo, k\bke\bey\bys\bse\beq\bq differs
- from k\bke\bey\byn\bna\bam\bme\be above in that strings denoting an entire key sequence may
- be specified by placing the sequence within double quotes. Some GNU
- Emacs style key escapes can be used, as in the following example, but
+ In the second form, "\b"k\bke\bey\bys\bse\beq\bq"\b":_\bf_\bu_\bn_\bc_\bt_\bi_\bo_\bn_\b-_\bn_\ba_\bm_\be or _\bm_\ba_\bc_\br_\bo, k\bke\bey\bys\bse\beq\bq differs
+ from k\bke\bey\byn\bna\bam\bme\be above in that strings denoting an entire key sequence may
+ be specified by placing the sequence within double quotes. Some GNU
+ Emacs style key escapes can be used, as in the following example, but
the symbolic character names are not recognized.
"\C-u": universal-argument
"\e[11~": "Function Key 1"
In this example, _\bC_\b-_\bu is again bound to the function u\bun\bni\biv\bve\ber\brs\bsa\bal\bl-\b-a\bar\brg\bgu\bum\bme\ben\bnt\bt.
- _\bC_\b-_\bx _\bC_\b-_\br is bound to the function r\bre\be-\b-r\bre\bea\bad\bd-\b-i\bin\bni\bit\bt-\b-f\bfi\bil\ble\be, and _\bE_\bS_\bC _\b[ _\b1 _\b1 _\b~ is
+ _\bC_\b-_\bx _\bC_\b-_\br is bound to the function r\bre\be-\b-r\bre\bea\bad\bd-\b-i\bin\bni\bit\bt-\b-f\bfi\bil\ble\be, and _\bE_\bS_\bC _\b[ _\b1 _\b1 _\b~ is
bound to insert the text ``Function Key 1''.
The full set of GNU Emacs style escape sequences is
\\b\"\b" literal "
\\b\'\b' literal '
- In addition to the GNU Emacs style escape sequences, a second set of
+ In addition to the GNU Emacs style escape sequences, a second set of
backslash escapes is available:
\\b\a\ba alert (bell)
\\b\b\bb backspace
\\b\r\br carriage return
\\b\t\bt horizontal tab
\\b\v\bv vertical tab
- \\b\_\bn_\bn_\bn the eight-bit character whose value is the octal value
+ \\b\_\bn_\bn_\bn the eight-bit character whose value is the octal value
_\bn_\bn_\bn (one to three digits)
- \\b\x\bx_\bH_\bH the eight-bit character whose value is the hexadecimal
+ \\b\x\bx_\bH_\bH the eight-bit character whose value is the hexadecimal
value _\bH_\bH (one or two hex digits)
When entering the text of a macro, single or double quotes must be used
to indicate a macro definition. Unquoted text is assumed to be a func-
- tion name. In the macro body, the backslash escapes described above
- are expanded. Backslash will quote any other character in the macro
+ tion name. In the macro body, the backslash escapes described above
+ are expanded. Backslash will quote any other character in the macro
text, including " and '.
- B\bBa\bas\bsh\bh allows the current readline key bindings to be displayed or modi-
- fied with the b\bbi\bin\bnd\bd builtin command. The editing mode may be switched
- during interactive use by using the -\b-o\bo option to the s\bse\bet\bt builtin com-
+ B\bBa\bas\bsh\bh allows the current readline key bindings to be displayed or modi-
+ fied with the b\bbi\bin\bnd\bd builtin command. The editing mode may be switched
+ during interactive use by using the -\b-o\bo option to the s\bse\bet\bt builtin com-
mand (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).
R\bRe\bea\bad\bdl\bli\bin\bne\be V\bVa\bar\bri\bia\bab\bbl\ble\bes\bs
s\bse\bet\bt _\bv_\ba_\br_\bi_\ba_\bb_\bl_\be_\b-_\bn_\ba_\bm_\be _\bv_\ba_\bl_\bu_\be
or using the b\bbi\bin\bnd\bd builtin command (see S\bSH\bHE\bEL\bLL\bL B\bBU\bUI\bIL\bLT\bTI\bIN\bN C\bCO\bOM\bMM\bMA\bAN\bND\bDS\bS below).
- Except where noted, readline variables can take the values O\bOn\bn or O\bOf\bff\bf
- (without regard to case). Unrecognized variable names are ignored.
- When a variable value is read, empty or null values, "on" (case-insen-
+ Except where noted, readline variables can take the values O\bOn\bn or O\bOf\bff\bf
+ (without regard to case). Unrecognized variable names are ignored.
+ When a variable value is read, empty or null values, "on" (case-insen-
sitive), and "1" are equivalent to O\bOn\bn. All other values are equivalent
to O\bOf\bff\bf. The variables and their default values are:
a\bac\bct\bti\biv\bve\be-\b-r\bre\beg\bgi\bio\bon\bn-\b-s\bst\bta\bar\brt\bt-\b-c\bco\bol\blo\bor\br
- A string variable that controls the text color and background
- when displaying the text in the active region (see the descrip-
- tion of e\ben\bna\bab\bbl\ble\be-\b-a\bac\bct\bti\biv\bve\be-\b-r\bre\beg\bgi\bio\bon\bn below). This string must not take
+ A string variable that controls the text color and background
+ when displaying the text in the active region (see the descrip-
+ tion of e\ben\bna\bab\bbl\ble\be-\b-a\bac\bct\bti\biv\bve\be-\b-r\bre\beg\bgi\bio\bon\bn below). This string must not take
up any physical character positions on the display, so it should
- consist only of terminal escape sequences. It is output to the
- terminal before displaying the text in the active region. This
- variable is reset to the default value whenever the terminal
- type changes. The default value is the string that puts the
- terminal in standout mode, as obtained from the terminal's ter-
+ consist only of terminal escape sequences. It is output to the
+ terminal before displaying the text in the active region. This
+ variable is reset to the default value whenever the terminal
+ type changes. The default value is the string that puts the
+ terminal in standout mode, as obtained from the terminal's ter-
minfo description. A sample value might be "\e[01;33m".
a\bac\bct\bti\biv\bve\be-\b-r\bre\beg\bgi\bio\bon\bn-\b-e\ben\bnd\bd-\b-c\bco\bol\blo\bor\br
- A string variable that "undoes" the effects of a\bac\bct\bti\biv\bve\be-\b-r\bre\be-\b-
- g\bgi\bio\bon\bn-\b-s\bst\bta\bar\brt\bt-\b-c\bco\bol\blo\bor\br and restores "normal" terminal display appear-
- ance after displaying text in the active region. This string
- must not take up any physical character positions on the dis-
- play, so it should consist only of terminal escape sequences.
- It is output to the terminal after displaying the text in the
- active region. This variable is reset to the default value
- whenever the terminal type changes. The default value is the
- string that restores the terminal from standout mode, as ob-
+ A string variable that "undoes" the effects of a\bac\bct\bti\biv\bve\be-\b-r\bre\be-\b-
+ g\bgi\bio\bon\bn-\b-s\bst\bta\bar\brt\bt-\b-c\bco\bol\blo\bor\br and restores "normal" terminal display appear-
+ ance after displaying text in the active region. This string
+ must not take up any physical character positions on the dis-
+ play, so it should consist only of terminal escape sequences.
+ It is output to the terminal after displaying the text in the
+ active region. This variable is reset to the default value
+ whenever the terminal type changes. The default value is the
+ string that restores the terminal from standout mode, as ob-
tained from the terminal's terminfo description. A sample value
might be "\e[0m".
b\bbe\bel\bll\bl-\b-s\bst\bty\byl\ble\be (\b(a\bau\bud\bdi\bib\bbl\ble\be)\b)
- Controls what happens when readline wants to ring the terminal
+ Controls what happens when readline wants to ring the terminal
bell. If set to n\bno\bon\bne\be, readline never rings the bell. If set to
- v\bvi\bis\bsi\bib\bbl\ble\be, readline uses a visible bell if one is available. If
+ v\bvi\bis\bsi\bib\bbl\ble\be, readline uses a visible bell if one is available. If
set to a\bau\bud\bdi\bib\bbl\ble\be, readline attempts to ring the terminal's bell.
b\bbi\bin\bnd\bd-\b-t\btt\bty\by-\b-s\bsp\bpe\bec\bci\bia\bal\bl-\b-c\bch\bha\bar\brs\bs (\b(O\bOn\bn)\b)
- If set to O\bOn\bn, readline attempts to bind the control characters
+ If set to O\bOn\bn, readline attempts to bind the control characters
treated specially by the kernel's terminal driver to their read-
line equivalents.
b\bbl\bli\bin\bnk\bk-\b-m\bma\bat\btc\bch\bhi\bin\bng\bg-\b-p\bpa\bar\bre\ben\bn (\b(O\bOf\bff\bf)\b)
If set to O\bOn\bn, readline attempts to briefly move the cursor to an
opening parenthesis when a closing parenthesis is inserted.
c\bco\bol\blo\bor\bre\bed\bd-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-p\bpr\bre\bef\bfi\bix\bx (\b(O\bOf\bff\bf)\b)
- If set to O\bOn\bn, when listing completions, readline displays the
+ If set to O\bOn\bn, when listing completions, readline displays the
common prefix of the set of possible completions using a differ-
- ent color. The color definitions are taken from the value of
+ ent color. The color definitions are taken from the value of
the L\bLS\bS_\b_C\bCO\bOL\bLO\bOR\bRS\bS environment variable. If there is a color defini-
- tion in $\b$L\bLS\bS_\b_C\bCO\bOL\bLO\bOR\bRS\bS for the custom suffix "readline-colored-com-
- pletion-prefix", readline uses this color for the common prefix
+ tion in $\b$L\bLS\bS_\b_C\bCO\bOL\bLO\bOR\bRS\bS for the custom suffix "readline-colored-com-
+ pletion-prefix", readline uses this color for the common prefix
instead of its default.
c\bco\bol\blo\bor\bre\bed\bd-\b-s\bst\bta\bat\bts\bs (\b(O\bOf\bff\bf)\b)
- If set to O\bOn\bn, readline displays possible completions using dif-
- ferent colors to indicate their file type. The color defini-
- tions are taken from the value of the L\bLS\bS_\b_C\bCO\bOL\bLO\bOR\bRS\bS environment
+ If set to O\bOn\bn, readline displays possible completions using dif-
+ ferent colors to indicate their file type. The color defini-
+ tions are taken from the value of the L\bLS\bS_\b_C\bCO\bOL\bLO\bOR\bRS\bS environment
variable.
c\bco\bom\bmm\bme\ben\bnt\bt-\b-b\bbe\beg\bgi\bin\bn (\b(`\b``\b`#\b#'\b''\b')\b)
- The string that is inserted when the readline i\bin\bns\bse\ber\brt\bt-\b-c\bco\bom\bmm\bme\ben\bnt\bt
+ The string that is inserted when the readline i\bin\bns\bse\ber\brt\bt-\b-c\bco\bom\bmm\bme\ben\bnt\bt
command is executed. This command is bound to M\bM-\b-#\b# in emacs mode
and to #\b# in vi command mode.
c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-d\bdi\bis\bsp\bpl\bla\bay\by-\b-w\bwi\bid\bdt\bth\bh (\b(-\b-1\b1)\b)
- The number of screen columns used to display possible matches
- when performing completion. The value is ignored if it is less
- than 0 or greater than the terminal screen width. A value of 0
- will cause matches to be displayed one per line. The default
+ The number of screen columns used to display possible matches
+ when performing completion. The value is ignored if it is less
+ than 0 or greater than the terminal screen width. A value of 0
+ will cause matches to be displayed one per line. The default
value is -1.
c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-i\big\bgn\bno\bor\bre\be-\b-c\bca\bas\bse\be (\b(O\bOf\bff\bf)\b)
If set to O\bOn\bn, readline performs filename matching and completion
in a case-insensitive fashion.
c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-m\bma\bap\bp-\b-c\bca\bas\bse\be (\b(O\bOf\bff\bf)\b)
- If set to O\bOn\bn, and c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-i\big\bgn\bno\bor\bre\be-\b-c\bca\bas\bse\be is enabled, readline
- treats hyphens (_\b-) and underscores (_\b_) as equivalent when per-
+ If set to O\bOn\bn, and c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-i\big\bgn\bno\bor\bre\be-\b-c\bca\bas\bse\be is enabled, readline
+ treats hyphens (_\b-) and underscores (_\b_) as equivalent when per-
forming case-insensitive filename matching and completion.
c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-p\bpr\bre\bef\bfi\bix\bx-\b-d\bdi\bis\bsp\bpl\bla\bay\by-\b-l\ble\ben\bng\bgt\bth\bh (\b(0\b0)\b)
- The length in characters of the common prefix of a list of pos-
- sible completions that is displayed without modification. When
- set to a value greater than zero, common prefixes longer than
- this value are replaced with an ellipsis when displaying possi-
+ The length in characters of the common prefix of a list of pos-
+ sible completions that is displayed without modification. When
+ set to a value greater than zero, common prefixes longer than
+ this value are replaced with an ellipsis when displaying possi-
ble completions.
c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn-\b-q\bqu\bue\ber\bry\by-\b-i\bit\bte\bem\bms\bs (\b(1\b10\b00\b0)\b)
- This determines when the user is queried about viewing the num-
- ber of possible completions generated by the p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\be-\b-
- t\bti\bio\bon\bns\bs command. It may be set to any integer value greater than
- or equal to zero. If the number of possible completions is
- greater than or equal to the value of this variable, readline
- will ask whether or not the user wishes to view them; otherwise
- they are simply listed on the terminal. A zero value means
+ This determines when the user is queried about viewing the num-
+ ber of possible completions generated by the p\bpo\bos\bss\bsi\bib\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\be-\b-
+ t\bti\bio\bon\bns\bs command. It may be set to any integer value greater than
+ or equal to zero. If the number of possible completions is
+ greater than or equal to the value of this variable, readline
+ will ask whether or not the user wishes to view them; otherwise
+ they are simply listed on the terminal. A zero value means
readline should never ask; negative values are treated as zero.
c\bco\bon\bnv\bve\ber\brt\bt-\b-m\bme\bet\bta\ba (\b(O\bOn\bn)\b)
- If set to O\bOn\bn, readline will convert characters with the eighth
+ If set to O\bOn\bn, readline will convert characters with the eighth
bit set to an ASCII key sequence by stripping the eighth bit and
- prefixing an escape character (in effect, using escape as the
- _\bm_\be_\bt_\ba _\bp_\br_\be_\bf_\bi_\bx). The default is _\bO_\bn, but readline will set it to
+ prefixing an escape character (in effect, using escape as the
+ _\bm_\be_\bt_\ba _\bp_\br_\be_\bf_\bi_\bx). The default is _\bO_\bn, but readline will set it to
_\bO_\bf_\bf if the locale contains eight-bit characters.
d\bdi\bis\bsa\bab\bbl\ble\be-\b-c\bco\bom\bmp\bpl\ble\bet\bti\bio\bon\bn (\b(O\bOf\bff\bf)\b)
If set to O\bOn\bn, readline will inhibit word completion. Completion
- characters will be inserted into the line as if they had been
+ characters will be inserted into the line as if they had been
mapped to s\bse\bel\blf\bf-\b-i\bin\bns\bse\ber\brt\bt.
e\bec\bch\bho\bo-\b-c\bco\bon\bnt\btr\bro\bol\bl-\b-c\bch\bha\bar\bra\bac\bct\bte\ber\brs\bs (\b(O\bOn\bn)\b)
- When set to O\bOn\bn, on operating systems that indicate they support
+ When set to O\bOn\bn, on operating systems that indicate they support
it, readline echoes a character corresponding to a signal gener-
ated from the keyboard.
e\bed\bdi\bit\bti\bin\bng\bg-\b-m\bmo\bod\bde\be (\b(e\bem\bma\bac\bcs\bs)\b)
ilar to _\bE_\bm_\ba_\bc_\bs or _\bv_\bi. e\bed\bdi\bit\bti\bin\bng\bg-\b-m\bmo\bod\bde\be can be set to either e\bem\bma\bac\bcs\bs or
v\bvi\bi.
e\bem\bma\bac\bcs\bs-\b-m\bmo\bod\bde\be-\b-s\bst\btr\bri\bin\bng\bg (\b(@\b@)\b)
- If the _\bs_\bh_\bo_\bw_\b-_\bm_\bo_\bd_\be_\b-_\bi_\bn_\b-_\bp_\br_\bo_\bm_\bp_\bt variable is enabled, this string is
+ If the _\bs_\bh_\bo_\bw_\b-_\bm_\bo_\bd_\be_\b-_\bi_\bn_\b-_\bp_\br_\bo_\bm_\bp_\bt variable is enabled, this string is
displayed immediately before the last line of the primary prompt
when emacs editing mode is active. The value is expanded like a
- key binding, so the standard set of meta- and control prefixes
- and backslash escape sequences is available. Use the \1 and \2
- escapes to begin and end sequences of non-printing characters,
- which can be used to embed a terminal control sequence into the
+ key binding, so the standard set of meta- and control prefixes
+ and backslash escape sequences is available. Use the \1 and \2
+ escapes to begin and end sequences of non-printing characters,
+ which can be used to embed a terminal control sequence into the
mode string.
e\ben\bna\bab\bbl\ble\be-\b-a\bac\bct\bti\biv\bve\be-\b-r\bre\beg\bgi\bio\bon\bn (\b(O\bOn\bn)\b)
- The _\bp_\bo_\bi_\bn_\bt is the current cursor position, and _\bm_\ba_\br_\bk refers to a
- saved cursor position. The text between the point and mark is
- referred to as the _\br_\be_\bg_\bi_\bo_\bn. When this variable is set to _\bO_\bn,
- readline allows certain commands to designate the region as _\ba_\bc_\b-
- _\bt_\bi_\bv_\be. When the region is active, readline highlights the text
- in the region using the value of the a\bac\bct\bti\biv\bve\be-\b-r\bre\beg\bgi\bio\bon\bn-\b-s\bst\bta\bar\brt\bt-\b-c\bco\bol\blo\bor\br,
- which defaults to the string that enables the terminal's stand-
- out mode. The active region shows the text inserted by brack-
- eted-paste and any matching text found by incremental and non-
+ The _\bp_\bo_\bi_\bn_\bt is the current cursor position, and _\bm_\ba_\br_\bk refers to a
+ saved cursor position. The text between the point and mark is
+ referred to as the _\br_\be_\bg_\bi_\bo_\bn. When this variable is set to _\bO_\bn,
+ readline allows certain commands to designate the region as _\ba_\bc_\b-
+ _\bt_\bi_\bv_\be. When the region is active, readline highlights the text
+ in the region using the value of the a\bac\bct\bti\biv\bve\be-\b-r\bre\beg\bgi\bio\bon\bn-\b-s\bst\bta\bar\brt\bt-\b-c\bco\bol\blo\bor\br,
+ which defaults to the string that enables the terminal's stand-
+ out mode. The active region shows the text inserted by brack-
+ eted-paste and any matching text found by incremental and non-
incremental history searches.
e\ben\bna\bab\bbl\ble\be-\b-b\bbr\bra\bac\bck\bke\bet\bte\bed\bd-\b-p\bpa\bas\bst\bte\be (\b(O\bOn\bn)\b)
- When set to O\bOn\bn, readline will configure the terminal in a way
- that will enable it to insert each paste into the editing buffer
- as a single string of characters, instead of treating each char-
- acter as if it had been read from the keyboard. This can pre-
- vent pasted characters from being interpreted as editing com-
- mands.
+ When set to O\bOn\bn, readline configures the terminal to insert each
+ paste into the editing buffer as a single string of characters,
+ instead of treating each character as if it had been read from
+ the keyboard. This prevents readline from executing any editing
+ commands bound to key sequences appearing in the pasted text.
e\ben\bna\bab\bbl\ble\be-\b-k\bke\bey\byp\bpa\bad\bd (\b(O\bOf\bff\bf)\b)
When set to O\bOn\bn, readline will try to enable the application key-
pad when it is called. Some systems need this to enable the ar-
-GNU Bash 5.2 2022 February 10 BASH(1)
+GNU Bash 5.2 2022 March 11 BASH(1)
bashref.texi.
This text is a brief description of the features that are present in the
-Bash shell (version 5.2, 5 February 2022).
+Bash shell (version 5.2, 24 February 2022).
- This is Edition 5.2, last updated 5 February 2022, of 'The GNU Bash
+ This is Edition 5.2, last updated 24 February 2022, of 'The GNU Bash
Reference Manual', for 'Bash', Version 5.2.
Copyright (C) 1988-2022 Free Software Foundation, Inc.
*************
This text is a brief description of the features that are present in the
-Bash shell (version 5.2, 5 February 2022). The Bash home page is
+Bash shell (version 5.2, 24 February 2022). The Bash home page is
<http://www.gnu.org/software/bash/>.
- This is Edition 5.2, last updated 5 February 2022, of 'The GNU Bash
+ This is Edition 5.2, last updated 24 February 2022, of 'The GNU Bash
Reference Manual', for 'Bash', Version 5.2.
Bash contains features that appear in other popular shells, and some
last command executed before the 'return'.
Variables local to the function may be declared with the 'local'
-builtin. These variables are visible only to the function and the
-commands it invokes. This is particularly important when a shell
-function calls other functions.
+builtin ("local variables"). Ordinarily, variables and their values are
+shared between a function and its caller. These variables are visible
+only to the function and the commands it invokes. This is particularly
+important when a shell function calls other functions.
+
+ In the following description, the "current scope" is a currently-
+executing function. Previous scopes consist of that function's caller
+and so on, back to the "global" scope, where the shell is not executing
+any shell function. Consequently, a local variable at the current local
+scope is a variable declared using the 'local' or 'declare' builtins in
+the function that is currently executing.
Local variables "shadow" variables with the same name declared at
previous scopes. For instance, a local variable declared in a function
variable is local to the current scope, 'unset' will unset it; otherwise
the unset will refer to the variable found in any calling scope as
described above. If a variable at the current local scope is unset, it
-will remain so until it is reset in that scope or until the function
-returns. Once the function returns, any instance of the variable at a
-previous scope will become visible. If the unset acts on a variable at
-a previous scope, any instance of a variable with that name that had
-been shadowed will become visible.
+will remain so (appearing as unset) until it is reset in that scope or
+until the function returns. Once the function returns, any instance of
+the variable at a previous scope will become visible. If the unset acts
+on a variable at a previous scope, any instance of a variable with that
+name that had been shadowed will become visible (see below how
+'localvar_unset'shell option changes this behavior).
Function names and definitions may be listed with the '-f' option to
the 'declare' ('typeset') builtin command (*note Bash Builtins::). The
'${PARAMETER:OFFSET:LENGTH}'
This is referred to as Substring Expansion. It expands to up to
LENGTH characters of the value of PARAMETER starting at the
- character specified by OFFSET. If PARAMETER is '@', an indexed
- array subscripted by '@' or '*', or an associative array name, the
- results differ as described below. If LENGTH is omitted, it
- expands to the substring of the value of PARAMETER starting at the
- character specified by OFFSET and extending to the end of the
+ character specified by OFFSET. If PARAMETER is '@' or '*', an
+ indexed array subscripted by '@' or '*', or an associative array
+ name, the results differ as described below. If LENGTH is omitted,
+ it expands to the substring of the value of PARAMETER starting at
+ the character specified by OFFSET and extending to the end of the
value. LENGTH and OFFSET are arithmetic expressions (*note Shell
Arithmetic::).
$ echo ${array[0]: -7:-2}
bcdef
- If PARAMETER is '@', the result is LENGTH positional parameters
- beginning at OFFSET. A negative OFFSET is taken relative to one
- greater than the greatest positional parameter, so an offset of -1
- evaluates to the last positional parameter. It is an expansion
- error if LENGTH evaluates to a number less than zero.
+ If PARAMETER is '@' or '*', the result is LENGTH positional
+ parameters beginning at OFFSET. A negative OFFSET is taken
+ relative to one greater than the greatest positional parameter, so
+ an offset of -1 evaluates to the last positional parameter. It is
+ an expansion error if LENGTH evaluates to a number less than zero.
The following examples illustrate substring expansion using
positional parameters:
than the maximum index of NAME, so negative indices count back from the
end of the array, and an index of -1 references the last element.
+ The '+=' operator will append to an array variable when assigning
+using the compound assignment syntax; see *note Shell Parameters::
+above.
+
Any element of an array may be referenced using '${NAME[SUBSCRIPT]}'.
The braces are required to avoid conflicts with the shell's filename
expansion operators. If the SUBSCRIPT is '@' or '*', the word expands
non-incremental history searches. The default is 'On'.
'enable-bracketed-paste'
- When set to 'On', Readline will configure the terminal in a
- way that will enable it to insert each paste into the editing
- buffer as a single string of characters, instead of treating
- each character as if it had been read from the keyboard. This
- can prevent pasted characters from being interpreted as
- editing commands. The default is 'On'.
+ When set to 'On', Readline configures the terminal to insert
+ each paste into the editing buffer as a single string of
+ characters, instead of treating each character as if it had
+ been read from the keyboard. This is called putting the
+ terminal into "bracketed paste mode"; it prevents Readline
+ from executing any editing commands bound to key sequences
+ appearing in the pasted text. The default is 'On'.
'enable-keypad'
When set to 'on', Readline will try to enable the application
* enable-bracketed-paste: Readline Init File Syntax.
(line 185)
* enable-keypad: Readline Init File Syntax.
- (line 193)
+ (line 194)
* ENV: Bash Variables. (line 279)
* EPOCHREALTIME: Bash Variables. (line 284)
* EPOCHSECONDS: Bash Variables. (line 292)
* EUID: Bash Variables. (line 299)
* EXECIGNORE: Bash Variables. (line 303)
* expand-tilde: Readline Init File Syntax.
- (line 204)
+ (line 205)
* FCEDIT: Bash Variables. (line 316)
* FIGNORE: Bash Variables. (line 320)
* FUNCNAME: Bash Variables. (line 326)
* HISTFILESIZE: Bash Variables. (line 402)
* HISTIGNORE: Bash Variables. (line 413)
* history-preserve-point: Readline Init File Syntax.
- (line 208)
+ (line 209)
* history-size: Readline Init File Syntax.
- (line 214)
+ (line 215)
* HISTSIZE: Bash Variables. (line 433)
* HISTTIMEFORMAT: Bash Variables. (line 440)
* HOME: Bourne Shell Variables.
(line 13)
* horizontal-scroll-mode: Readline Init File Syntax.
- (line 223)
+ (line 224)
* HOSTFILE: Bash Variables. (line 448)
* HOSTNAME: Bash Variables. (line 459)
* HOSTTYPE: Bash Variables. (line 462)
(line 18)
* IGNOREEOF: Bash Variables. (line 465)
* input-meta: Readline Init File Syntax.
- (line 232)
+ (line 233)
* INPUTRC: Bash Variables. (line 475)
* INSIDE_EMACS: Bash Variables. (line 479)
* isearch-terminators: Readline Init File Syntax.
- (line 240)
+ (line 241)
* keymap: Readline Init File Syntax.
- (line 247)
+ (line 248)
* LANG: Creating Internationalized Scripts.
(line 51)
* LANG <1>: Bash Variables. (line 485)
(line 27)
* MAPFILE: Bash Variables. (line 540)
* mark-modified-lines: Readline Init File Syntax.
- (line 277)
+ (line 278)
* mark-symlinked-directories: Readline Init File Syntax.
- (line 282)
+ (line 283)
* match-hidden-files: Readline Init File Syntax.
- (line 287)
+ (line 288)
* menu-complete-display-prefix: Readline Init File Syntax.
- (line 294)
+ (line 295)
* meta-flag: Readline Init File Syntax.
- (line 232)
+ (line 233)
* OLDPWD: Bash Variables. (line 544)
* OPTARG: Bourne Shell Variables.
(line 34)
(line 38)
* OSTYPE: Bash Variables. (line 551)
* output-meta: Readline Init File Syntax.
- (line 299)
+ (line 300)
* page-completions: Readline Init File Syntax.
- (line 305)
+ (line 306)
* PATH: Bourne Shell Variables.
(line 42)
* PIPESTATUS: Bash Variables. (line 554)
* READLINE_POINT: Bash Variables. (line 626)
* REPLY: Bash Variables. (line 630)
* revert-all-at-newline: Readline Init File Syntax.
- (line 315)
+ (line 316)
* SECONDS: Bash Variables. (line 633)
* SHELL: Bash Variables. (line 642)
* SHELLOPTS: Bash Variables. (line 647)
* SHLVL: Bash Variables. (line 656)
* show-all-if-ambiguous: Readline Init File Syntax.
- (line 321)
+ (line 322)
* show-all-if-unmodified: Readline Init File Syntax.
- (line 327)
+ (line 328)
* show-mode-in-prompt: Readline Init File Syntax.
- (line 336)
+ (line 337)
* skip-completed-text: Readline Init File Syntax.
- (line 342)
+ (line 343)
* SRANDOM: Bash Variables. (line 661)
* TEXTDOMAIN: Creating Internationalized Scripts.
(line 51)
* TMPDIR: Bash Variables. (line 720)
* UID: Bash Variables. (line 724)
* vi-cmd-mode-string: Readline Init File Syntax.
- (line 355)
+ (line 356)
* vi-ins-mode-string: Readline Init File Syntax.
- (line 366)
+ (line 367)
* visible-stats: Readline Init File Syntax.
- (line 377)
+ (line 378)
\1f
File: bashref.info, Node: Function Index, Next: Concept Index, Prev: Variable Index, Up: Indexes
\1f
Tag Table:
-Node: Top\7f895
-Node: Introduction\7f2813
-Node: What is Bash?\7f3029
-Node: What is a shell?\7f4143
-Node: Definitions\7f6681
-Node: Basic Shell Features\7f9632
-Node: Shell Syntax\7f10851
-Node: Shell Operation\7f11877
-Node: Quoting\7f13170
-Node: Escape Character\7f14474
-Node: Single Quotes\7f14959
-Node: Double Quotes\7f15307
-Node: ANSI-C Quoting\7f16585
-Node: Locale Translation\7f17895
-Node: Creating Internationalized Scripts\7f19206
-Node: Comments\7f23323
-Node: Shell Commands\7f23941
-Node: Reserved Words\7f24879
-Node: Simple Commands\7f25635
-Node: Pipelines\7f26289
-Node: Lists\7f29248
-Node: Compound Commands\7f31043
-Node: Looping Constructs\7f32055
-Node: Conditional Constructs\7f34550
-Node: Command Grouping\7f48894
-Node: Coprocesses\7f50372
-Node: GNU Parallel\7f53035
-Node: Shell Functions\7f53952
-Node: Shell Parameters\7f61243
-Node: Positional Parameters\7f65631
-Node: Special Parameters\7f66533
-Node: Shell Expansions\7f69747
-Node: Brace Expansion\7f71874
-Node: Tilde Expansion\7f74608
-Node: Shell Parameter Expansion\7f77229
-Node: Command Substitution\7f95566
-Node: Arithmetic Expansion\7f96921
-Node: Process Substitution\7f97889
-Node: Word Splitting\7f99009
-Node: Filename Expansion\7f100953
-Node: Pattern Matching\7f103702
-Node: Quote Removal\7f108310
-Node: Redirections\7f108605
-Node: Executing Commands\7f118265
-Node: Simple Command Expansion\7f118935
-Node: Command Search and Execution\7f121045
-Node: Command Execution Environment\7f123423
-Node: Environment\7f126458
-Node: Exit Status\7f128121
-Node: Signals\7f129905
-Node: Shell Scripts\7f133354
-Node: Shell Builtin Commands\7f136381
-Node: Bourne Shell Builtins\7f138419
-Node: Bash Builtins\7f159880
-Node: Modifying Shell Behavior\7f190736
-Node: The Set Builtin\7f191081
-Node: The Shopt Builtin\7f201682
-Node: Special Builtins\7f217594
-Node: Shell Variables\7f218573
-Node: Bourne Shell Variables\7f219010
-Node: Bash Variables\7f221114
-Node: Bash Features\7f253930
-Node: Invoking Bash\7f254943
-Node: Bash Startup Files\7f260956
-Node: Interactive Shells\7f266059
-Node: What is an Interactive Shell?\7f266469
-Node: Is this Shell Interactive?\7f267118
-Node: Interactive Shell Behavior\7f267933
-Node: Bash Conditional Expressions\7f271562
-Node: Shell Arithmetic\7f276204
-Node: Aliases\7f279148
-Node: Arrays\7f281761
-Node: The Directory Stack\7f288008
-Node: Directory Stack Builtins\7f288792
-Node: Controlling the Prompt\7f293052
-Node: The Restricted Shell\7f296017
-Node: Bash POSIX Mode\7f298627
-Node: Shell Compatibility Mode\7f310277
-Node: Job Control\7f318306
-Node: Job Control Basics\7f318766
-Node: Job Control Builtins\7f323768
-Node: Job Control Variables\7f329168
-Node: Command Line Editing\7f330324
-Node: Introduction and Notation\7f331995
-Node: Readline Interaction\7f333618
-Node: Readline Bare Essentials\7f334809
-Node: Readline Movement Commands\7f336592
-Node: Readline Killing Commands\7f337552
-Node: Readline Arguments\7f339470
-Node: Searching\7f340514
-Node: Readline Init File\7f342700
-Node: Readline Init File Syntax\7f343961
-Node: Conditional Init Constructs\7f367087
-Node: Sample Init File\7f371283
-Node: Bindable Readline Commands\7f374407
-Node: Commands For Moving\7f375611
-Node: Commands For History\7f377662
-Node: Commands For Text\7f382656
-Node: Commands For Killing\7f386305
-Node: Numeric Arguments\7f389338
-Node: Commands For Completion\7f390477
-Node: Keyboard Macros\7f394668
-Node: Miscellaneous Commands\7f395355
-Node: Readline vi Mode\7f401294
-Node: Programmable Completion\7f402201
-Node: Programmable Completion Builtins\7f409981
-Node: A Programmable Completion Example\7f420676
-Node: Using History Interactively\7f425923
-Node: Bash History Facilities\7f426607
-Node: Bash History Builtins\7f429612
-Node: History Interaction\7f434620
-Node: Event Designators\7f438240
-Node: Word Designators\7f439594
-Node: Modifiers\7f441354
-Node: Installing Bash\7f443165
-Node: Basic Installation\7f444302
-Node: Compilers and Options\7f448024
-Node: Compiling For Multiple Architectures\7f448765
-Node: Installation Names\7f450458
-Node: Specifying the System Type\7f452567
-Node: Sharing Defaults\7f453283
-Node: Operation Controls\7f453956
-Node: Optional Features\7f454914
-Node: Reporting Bugs\7f466132
-Node: Major Differences From The Bourne Shell\7f467407
-Node: GNU Free Documentation License\7f484257
-Node: Indexes\7f509434
-Node: Builtin Index\7f509888
-Node: Reserved Word Index\7f516715
-Node: Variable Index\7f519163
-Node: Function Index\7f535937
-Node: Concept Index\7f549721
+Node: Top\7f897
+Node: Introduction\7f2817
+Node: What is Bash?\7f3033
+Node: What is a shell?\7f4147
+Node: Definitions\7f6685
+Node: Basic Shell Features\7f9636
+Node: Shell Syntax\7f10855
+Node: Shell Operation\7f11881
+Node: Quoting\7f13174
+Node: Escape Character\7f14478
+Node: Single Quotes\7f14963
+Node: Double Quotes\7f15311
+Node: ANSI-C Quoting\7f16589
+Node: Locale Translation\7f17899
+Node: Creating Internationalized Scripts\7f19210
+Node: Comments\7f23327
+Node: Shell Commands\7f23945
+Node: Reserved Words\7f24883
+Node: Simple Commands\7f25639
+Node: Pipelines\7f26293
+Node: Lists\7f29252
+Node: Compound Commands\7f31047
+Node: Looping Constructs\7f32059
+Node: Conditional Constructs\7f34554
+Node: Command Grouping\7f48898
+Node: Coprocesses\7f50376
+Node: GNU Parallel\7f53039
+Node: Shell Functions\7f53956
+Node: Shell Parameters\7f61841
+Node: Positional Parameters\7f66229
+Node: Special Parameters\7f67131
+Node: Shell Expansions\7f70345
+Node: Brace Expansion\7f72472
+Node: Tilde Expansion\7f75206
+Node: Shell Parameter Expansion\7f77827
+Node: Command Substitution\7f96178
+Node: Arithmetic Expansion\7f97533
+Node: Process Substitution\7f98501
+Node: Word Splitting\7f99621
+Node: Filename Expansion\7f101565
+Node: Pattern Matching\7f104314
+Node: Quote Removal\7f108922
+Node: Redirections\7f109217
+Node: Executing Commands\7f118877
+Node: Simple Command Expansion\7f119547
+Node: Command Search and Execution\7f121657
+Node: Command Execution Environment\7f124035
+Node: Environment\7f127070
+Node: Exit Status\7f128733
+Node: Signals\7f130517
+Node: Shell Scripts\7f133966
+Node: Shell Builtin Commands\7f136993
+Node: Bourne Shell Builtins\7f139031
+Node: Bash Builtins\7f160492
+Node: Modifying Shell Behavior\7f191348
+Node: The Set Builtin\7f191693
+Node: The Shopt Builtin\7f202294
+Node: Special Builtins\7f218206
+Node: Shell Variables\7f219185
+Node: Bourne Shell Variables\7f219622
+Node: Bash Variables\7f221726
+Node: Bash Features\7f254542
+Node: Invoking Bash\7f255555
+Node: Bash Startup Files\7f261568
+Node: Interactive Shells\7f266671
+Node: What is an Interactive Shell?\7f267081
+Node: Is this Shell Interactive?\7f267730
+Node: Interactive Shell Behavior\7f268545
+Node: Bash Conditional Expressions\7f272174
+Node: Shell Arithmetic\7f276816
+Node: Aliases\7f279760
+Node: Arrays\7f282373
+Node: The Directory Stack\7f288764
+Node: Directory Stack Builtins\7f289548
+Node: Controlling the Prompt\7f293808
+Node: The Restricted Shell\7f296773
+Node: Bash POSIX Mode\7f299383
+Node: Shell Compatibility Mode\7f311033
+Node: Job Control\7f319062
+Node: Job Control Basics\7f319522
+Node: Job Control Builtins\7f324524
+Node: Job Control Variables\7f329924
+Node: Command Line Editing\7f331080
+Node: Introduction and Notation\7f332751
+Node: Readline Interaction\7f334374
+Node: Readline Bare Essentials\7f335565
+Node: Readline Movement Commands\7f337348
+Node: Readline Killing Commands\7f338308
+Node: Readline Arguments\7f340226
+Node: Searching\7f341270
+Node: Readline Init File\7f343456
+Node: Readline Init File Syntax\7f344717
+Node: Conditional Init Constructs\7f367916
+Node: Sample Init File\7f372112
+Node: Bindable Readline Commands\7f375236
+Node: Commands For Moving\7f376440
+Node: Commands For History\7f378491
+Node: Commands For Text\7f383485
+Node: Commands For Killing\7f387134
+Node: Numeric Arguments\7f390167
+Node: Commands For Completion\7f391306
+Node: Keyboard Macros\7f395497
+Node: Miscellaneous Commands\7f396184
+Node: Readline vi Mode\7f402123
+Node: Programmable Completion\7f403030
+Node: Programmable Completion Builtins\7f410810
+Node: A Programmable Completion Example\7f421505
+Node: Using History Interactively\7f426752
+Node: Bash History Facilities\7f427436
+Node: Bash History Builtins\7f430441
+Node: History Interaction\7f435449
+Node: Event Designators\7f439069
+Node: Word Designators\7f440423
+Node: Modifiers\7f442183
+Node: Installing Bash\7f443994
+Node: Basic Installation\7f445131
+Node: Compilers and Options\7f448853
+Node: Compiling For Multiple Architectures\7f449594
+Node: Installation Names\7f451287
+Node: Specifying the System Type\7f453396
+Node: Sharing Defaults\7f454112
+Node: Operation Controls\7f454785
+Node: Optional Features\7f455743
+Node: Reporting Bugs\7f466961
+Node: Major Differences From The Bourne Shell\7f468236
+Node: GNU Free Documentation License\7f485086
+Node: Indexes\7f510263
+Node: Builtin Index\7f510717
+Node: Reserved Word Index\7f517544
+Node: Variable Index\7f519992
+Node: Function Index\7f536766
+Node: Concept Index\7f550550
\1f
End Tag Table
projects / thirdparty / bash.git / commitdiff
