This document details the incompatibilites between this version of bash,
-bash-2.0, and the previous version, bash-1.14. These were discovered
-by alpha and beta testers, so they will likely be encountered by a
-significant number of users.
+bash-2.05, and the previous widely-available version, bash-1.14 (which
+is still the `standard' version for many Linux distributions). These
+were discovered by users of bash-2.x, so this list is not comprehensive.
1. Bash now uses a new quoting syntax, $"...", to do locale-specific
string translation. Users who have relied on the (undocumented)
"\C-\\": self-insert
6. A number of people complained above having to use ESC to terminate an
- incremental search, and asked for an alternate mechanism. Bash-2.0
- allows ^J to terminate the search without accepting the line. Use
- ^M to terminate the search and accept the line, as in bash-1.14.
+ incremental search, and asked for an alternate mechanism. Bash-2.03
+ uses the value of the settable readline variable `isearch-terminators'
+ to decide which characters should terminate an incremental search. If
+ that variable has not been set, ESC and Control-J will terminate a
+ search.
7. Some variables have been removed: MAIL_WARNING, notify, history_control,
command_oriented_history, glob_dot_filenames, allow_null_glob_expansion,
nolinks, hostname_completion_file, noclobber, no_exit_on_failed_exec, and
cdable_vars. Most of them are now implemented with the new `shopt'
- builtin; others were already implemented by `set'.
+ builtin; others were already implemented by `set'. Here is a list of
+ correspondences:
-8. The `ulimit' builtins now sets both hard and soft limits and reports the
- soft limit by default (when neither -H nor -S is specified). This is
- compatible with versions of sh and ksh that implement `ulimit'.
+ MAIL_WARNING shopt mailwarn
+ notify set -o notify
+ history_control HISTCONTROL
+ command_oriented_history shopt cmdhist
+ glob_dot_filenames shopt dotglob
+ allow_null_glob_expansion shopt nullglob
+ nolinks set -o physical
+ hostname_completion_file HOSTFILE
+ noclobber set -o noclobber
+ no_exit_on_failed_exec shopt execfail
+ cdable_vars shopt cdable_vars
+
+8. `ulimit' now sets both hard and soft limits and reports the soft limit
+ by default (when neither -H nor -S is specified). This is compatible
+ with versions of sh and ksh that implement `ulimit'. The bash-1.14
+ behavior of, for example,
+
+ ulimit -c 0
+
+ can be obtained with
+
+ ulimit -S -c 0
+
+ It may be useful to define an alias:
+
+ alias ulimit="ulimit -S"
+
+9. Bash-2.01 uses a new quoting syntax, $'...' to do ANSI-C string
+ translation. Backslash-escaped characters in ... are expanded and
+ replaced as specified by the ANSI C standard.
+
+10. The sourcing of startup files has changed somewhat. This is explained
+ more completely in the INVOCATION section of the manual page.
+
+ A non-interactive shell not named `sh' and not in posix mode reads
+ and executes commands from the file named by $BASH_ENV. A
+ non-interactive shell started by `su' and not in posix mode will read
+ startup files. No other non-interactive shells read any startup files.
+
+ An interactive shell started in posix mode reads and executes commands
+ from the file named by $ENV.
+
+11. The <> redirection operator was changed to conform to the POSIX.2 spec.
+ In the absence of any file descriptor specification preceding the `<>',
+ file descriptor 0 is used. In bash-1.14, this was the behavior only
+ when in POSIX mode. The bash-1.14 behavior may be obtained with
+
+ <>filename 1>&0
+
+12. The `alias' builtin now checks for invalid options and takes a `-p'
+ option to display output in POSIX mode. If you have old aliases beginning
+ with `-' or `+', you will have to add the `--' to the alias command
+ that declares them:
+
+ alias -x='chmod a-x' --> alias -- -x='chmod a-x'
+
+13. There was a bug in bash-1.14 and previous versions that caused it to
+ accept as valid syntax for loops of the form
+
+ for f in ; do ... ; done
+
+ This should be a syntax error, and bash-2.x treats it as such.
+
+14. The behavior of range specificiers within bracket matching expressions
+ in the pattern matcher (e.g., [A-Z]) depends on the current locale,
+ specifically the value of the LC_COLLATE environment variable. Setting
+ this variable to C or POSIX will result in the traditional ASCII behavior
+ for range comparisons. If the locale is set to something else, e.g.,
+ en_US (specified by the LANG or LC_ALL variables), collation order is
+ locale-dependent. For example, the en_US locale sorts the upper and
+ lower case letters like this:
+
+ AaBb...Zz
+
+ so a range specification like [A-Z] will match every letter except `z'.
+
+ The portable way to specify upper case letters is [:upper:] instead of
+ A-Z; lower case may be specified as [:lower:] instead of a-z.
+
+ Look at the manual pages for setlocale(3), strcoll(3), and, if it is
+ present, locale(1).
+
+ You can find your current locale information by running locale(1):
+
+ caleb.ins.cwru.edu(2)$ locale
+ LANG=en_US
+ LC_CTYPE="en_US"
+ LC_NUMERIC="en_US"
+ LC_TIME="en_US"
+ LC_COLLATE="en_US"
+ LC_MONETARY="en_US"
+ LC_MESSAGES="en_US"
+ LC_ALL=en_US
+
+ My advice is to put
+
+ export LC_COLLATE=C
+
+ into /etc/profile and inspect any shell scripts run from cron for
+ constructs like [A-Z]. This will prevent things like
+
+ rm [A-Z]*
+
+ from removing every file in the current directory except those beginning
+ with `z' and still allow individual users to change the collation order.
+ Users may put the above command into their own profiles as well, of course.
+
+15. Bash versions up to 1.14.7 included an undocumented `-l' operator to
+ the `test/[' builtin. It was a unary operator that expanded to the
+ length of its string argument. This let you do things like
+
+ test -l $variable -lt 20
+
+ for example.
+
+ This was included for backwards compatibility with old versions of the
+ Bourne shell, which did not provide an easy way to obtain the length of
+ the value of a shell variable.
+
+ This operator is not part of the POSIX standard, because one can (and
+ should) use ${#variable} to get the length of a variable's value.
+ Bash-2.x does not support it.
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