described here. (In fact, every @sc{gnu} program accepts (or should accept)
these options.)
+@vindex POSIXLY_CORRECT
+Normally options and operands can appear in any order, and programs act
+as if all the options appear before any operands. For example,
+@samp{sort -r passwd -t :} acts like @samp{sort -r -t : passwd}, since
+@samp{:} is an option-argument of @option{-t}. However, if the
+@env{POSIXLY_CORRECT} environment variable is set, options must appear
+before operands, unless otherwise specified for a particular command.
+
Some of these programs recognize the @samp{--help} and @samp{--version}
options only when one of them is the sole command line argument.
@cindex version number, finding
Print the version number, then exit successfully.
+@item --
+@opindex --
+@cindex option delimiter
+Delimit the option list. Later arguments, if any, are treated as
+operands even if they begin with @samp{-}. For example, @samp{sort --
+-r} reads from the file named @file{-r}.
+
@end table
+@cindex standard input
+@cindex standard output
+A single @samp{-} is not really an option, though it looks like one. It
+stands for standard input, or for standard output if that is clear from
+the context, and it can be used either as an operand or as an
+option-argument. For example, @samp{sort -o - -} outputs to standard
+output and reads from standard input, and is equivalent to plain
+@samp{sort}. Unless otherwise specified, @samp{-} can appear in any
+context that requires a file name.
@node Output of entire files
@chapter Output of entire files
@opindex -c
@opindex --show-control-chars
Print control characters using hat notation (e.g., @samp{^G}); print
-other unprintable characters in octal backslash notation. By default,
-unprintable characters are not changed.
+other nonprinting characters in octal backslash notation. By default,
+nonprinting characters are not changed.
@item -d
@itemx --double-space
@itemx --show-nonprinting
@opindex -v
@opindex --show-nonprinting
-Print unprintable characters in octal backslash notation.
+Print nonprinting characters in octal backslash notation.
@item -w @var{page_width}
@itemx --width=@var{page_width}
@table @samp
@item -c
+@itemx --check
@opindex -c
+@opindex --check
@cindex checking for sortedness
Check whether the given files are already sorted: if they are not all
sorted, print an error message and exit with a status of 1.
Otherwise, exit successfully.
@item -m
+@itemx --merge
@opindex -m
+@opindex --merge
@cindex merging sorted files
Merge the given files by sorting them as a group. Each input file must
always be individually sorted. It always works to sort instead of
Unless otherwise specified, all comparisons use the character
collating sequence specified by the @env{LC_COLLATE} locale.
-If any of the global options @samp{Mbdfinr} are given but no key fields
+If any of the global options @samp{bdfgiMnr} are given but no key fields
are specified, @code{sort} compares the entire lines according to the
global options.
Finally, as a last resort when all keys compare equal (or if no
ordering options were specified at all), @code{sort} compares the entire
lines. The last resort comparison
-honors the @samp{-r} global option. The @samp{-s} (stable) option
+honors the @option{--reverse} (@option{-r}) global option.
+The @option{--stable} (@option{-s}) option
disables this last-resort comparison so that lines in which all fields
compare equal are left in their original relative order. If no fields
-or global options are specified, @samp{-s} has no effect.
+or global options are specified, @option{--stable} (@option{-s}) has no
+effect.
@sc{gnu} @code{sort} (as specified for all @sc{gnu} utilities) has no limits on
input line length or restrictions on bytes allowed within lines. In
@vindex TMPDIR
If the environment variable @env{TMPDIR} is set, @code{sort} uses its
value as the directory for temporary files instead of @file{/tmp}. The
-@samp{-T @var{tempdir}} option in turn overrides the environment
-variable.
+@option{--temporary-directory} (@option{-T}) option in turn overrides
+the environment variable.
The following options affect the ordering of output lines. They may be
specified globally or as part of a specific key field. If no key
@table @samp
@item -b
+@itemx --ignore-leading-blanks
@opindex -b
+@opindex --ignore-leading-blanks
@cindex blanks, ignoring leading
@vindex LC_CTYPE
Ignore leading blanks when finding sort keys in each line.
The @env{LC_CTYPE} locale determines character types.
@item -d
+@itemx --dictionary-order
@opindex -d
+@opindex --dictionary-order
+@cindex dictionary order
@cindex phone directory order
@cindex telephone directory order
@vindex LC_CTYPE
The @env{LC_CTYPE} locale determines character types.
@item -f
+@itemx --ignore-case
@opindex -f
+@opindex --ignore-case
+@cindex ignoring case
@cindex case folding
@vindex LC_CTYPE
Fold lowercase characters into the equivalent uppercase characters when
-sorting so that, for example, @samp{b} and @samp{B} sort as equal.
+comparing so that, for example, @samp{b} and @samp{B} sort as equal.
The @env{LC_CTYPE} locale determines character types.
@item -g
+@itemx --general-numeric-sort
@opindex -g
+@opindex --general-numeric-sort
@cindex general numeric sort
@vindex LC_NUMERIC
Sort numerically, using the standard C function @code{strtod} to convert
@end itemize
Use this option only if there is no alternative; it is much slower than
-@samp{-n} and it can lose information when converting to floating point.
+@option{--numeric-sort} (@option{-n}) and it can lose information when
+converting to floating point.
@item -i
+@itemx --ignore-nonprinting
@opindex -i
+@opindex --ignore-nonprinting
+@cindex nonprinting characters, ignoring
@cindex unprintable characters, ignoring
@vindex LC_CTYPE
-Ignore unprintable characters.
+Ignore nonprinting characters.
The @env{LC_CTYPE} locale determines character types.
@item -M
+@itemx --month-sort
@opindex -M
+@opindex --month-sort
@cindex months, sorting by
@vindex LC_TIME
An initial string, consisting of any amount of whitespace, followed
determines the month spellings.
@item -n
+@itemx --numeric-sort
@opindex -n
+@opindex --numeric-sort
@cindex numeric sort
@vindex LC_NUMERIC
Sort numerically: the number begins each line; specifically, it consists
by a decimal-point character and zero or more digits. The @env{LC_NUMERIC}
locale specifies the decimal-point character and thousands separator.
-@code{sort -n} uses what might be considered an unconventional method
+Numeric sort uses what might be considered an unconventional method
to compare strings representing floating point numbers. Rather than
first converting each string to the C @code{double} type and then
-comparing those values, sort aligns the decimal-point characters in the two
+comparing those values, @command{sort} aligns the decimal-point
+characters in the two
strings and compares the strings a character at a time. One benefit
of using this approach is its speed. In practice this is much more
efficient than performing the two corresponding string-to-double (or even
on most systems.
Neither a leading @samp{+} nor exponential notation is recognized.
-To compare such strings numerically, use the @samp{-g} option.
+To compare such strings numerically, use the
+@option{--general-numeric-sort} (@option{-g}) option.
@item -r
+@itemx --reverse
@opindex -r
+@opindex --reverse
@cindex reverse sorting
Reverse the result of comparison, so that lines with greater key values
appear earlier in the output instead of later.
@table @samp
@item -o @var{output-file}
+@itemx --output=@var{output-file}
@opindex -o
+@opindex --output
@cindex overwriting of input, allowed
Write output to @var{output-file} instead of standard output.
If necessary, @command{sort} reads input before opening
@var{output-file}, so you can safely sort a file in place by using
-commands like @code{sort F -o F} and @code{cat F | sort -o F}.
+commands like @code{sort -o F F} and @code{cat F | sort -o F}.
+
+@vindex POSIXLY_CORRECT
+If @option{-c} is not also specified, @option{-o} may appear after an
+input file even if @env{POSIXLY_CORRECT} is set, e.g., @samp{sort F -o
+F}. Warning: this usage is obsolescent. Future versions of @sc{posix}
+will require that support for it be withdrawn. Portable scripts should
+specify @samp{-o @var{output-file}} before any input files.
@item -S @var{size}
+@itemx --buffer-size=@var{size}
@opindex -S
+@opindex --buffer-size
@cindex size for main memory sorting
Use a main-memory sort buffer of the given @var{size}. By default,
@var{size} is in units of 1,024 bytes. Appending @samp{%} causes
than @var{size}.
@item -t @var{separator}
+@itemx --field-separator=@var{separator}
@opindex -t
+@opindex --field-separator
@cindex field separator character
Use character @var{separator} as the field separator when finding the
sort keys in each line. By default, fields are separated by the empty
retain the field separators present between the endpoints of the range.
@item -T @var{tempdir}
+@itemx --temporary-directory=@var{tempdir}
@opindex -T
+@opindex --temporary-directory
@cindex temporary directory
@vindex TMPDIR
Use directory @var{tempdir} to store temporary files, overriding the
disks and controllers.
@item -u
+@itemx --unique
@opindex -u
+@opindex --unique
@cindex uniquifying output
-For the default case or the @samp{-m} option, only output the first
-of a sequence of lines that compare equal. For the @samp{-c} option,
+
+Normally, output only the first of a sequence of lines that compare
+equal. For the @option{--check} (@option{-c}) option,
check that no pair of consecutive lines compares equal.
@item -k @var{pos1}[,@var{pos2}]
+@itemx --key=@var{pos1}[,@var{pos2}]
@opindex -k
+@opindex --key
@cindex sort field
-The recommended, @sc{posix}, option for specifying a sort field. The field
+Specify a sort field that
consists of the part of the line between @var{pos1} and @var{pos2} (or the
end of the line, if @var{pos2} is omitted), @emph{inclusive}.
Fields and character positions are numbered starting with 1.
-So to sort on the second field, you'd use @samp{-k 2,2}
+So to sort on the second field, you'd use @samp{--key=2,2} (@samp{-k 2,2}).
See below for more examples.
@item -z
+@itemx --zero-terminated
@opindex -z
+@opindex --zero-terminated
@cindex sort zero-terminated lines
Treat the input as a set of lines, each terminated by a zero byte (@sc{ascii}
@sc{nul} (Null) character) instead of an @sc{ascii} @sc{lf} (Line Feed).
reliably handle arbitrary pathnames (even those which contain Line Feed
characters.)
-@item +@var{pos1}[-@var{pos2}]
+@item +@var{pos1} [-@var{pos2}]
The obsolescent, traditional option for specifying a sort field. The field
consists of the line between @var{pos1} and up to but @emph{not including}
@var{pos2} (or the end of the line if @var{pos2} is omitted). Fields
and character positions are numbered starting with 0. See below.
-Warning: the @samp{+@var{pos}} usage is obsolescent. Future versions of
+Warning: the @samp{+@var{pos1}} usage is obsolescent. Future versions of
@sc{posix} will require that support for it be withdrawn. Use
-@option{-k} instead.
+@option{--key} (@option{-k}) instead.
@end table
-In addition, when @sc{gnu} @code{sort} is invoked with exactly one argument,
-options @samp{--help} and @samp{--version} are recognized. @xref{Common
-options}.
-
Historical (BSD and System V) implementations of @code{sort} have
differed in their interpretation of some options, particularly
@samp{-b}, @samp{-f}, and @samp{-n}. @sc{gnu} sort follows the @sc{posix}
projects / thirdparty / coreutils.git / commitdiff
