1 This document details the incompatibilites between this version of bash,
2 bash-2.04, and the previous widely-available version, bash-1.14 (which
3 is still the `standard' version for many Linux distributions). These
4 were discovered by users of bash-2.x, so this list is not comprehensive.
6 1. Bash now uses a new quoting syntax, $"...", to do locale-specific
7 string translation. Users who have relied on the (undocumented)
8 behavior of bash-1.14 will have to change their scripts. For
9 instance, if you are doing something like this to get the value of
10 a variable whose name is the value of a second variable:
14 you will have to change to a different syntax.
16 This capability is directly supported by bash-2.0:
20 This alternate syntax will work portably between bash-1.14 and bash-2.0:
24 2. One of the bugs fixed in the YACC grammar tightens up the rules
25 concerning group commands ( {...} ). The `list' that composes the
26 body of the group command must be terminated by a newline or
27 semicolon. That's because the braces are reserved words, and are
28 recognized as such only when a reserved word is legal. This means
29 that while bash-1.14 accepted shell function definitions like this:
33 bash-2.0 requires this:
37 This is also an issue for commands like this:
39 mkdir dir || { echo 'could not mkdir' ; exit 1; }
41 The syntax required by bash-2.0 is also accepted by bash-1.14.
43 3. The options to `bind' have changed to make them more consistent with
44 the rest of the bash builtins. If you are using `bind -d' to list
45 the readline keybindings in a form that can be re-read, use `bind -p'
46 instead. If you were using `bind -v' to list the keybindings, use
49 4. The `long' invocation options must now be prefixed by `--' instead
50 of `-'. (The old form is still accepted, for the time being.)
52 5. There was a bug in the version of readline distributed with bash-1.14
53 that caused it to write badly-formatted key bindings when using
54 `bind -d'. The only key sequences that were affected are C-\ (which
55 should appear as \C-\\ in a key binding) and C-" (which should appear
56 as \C-\"). If these key sequences appear in your inputrc, as, for
61 they will need to be changed to something like the following:
65 6. A number of people complained above having to use ESC to terminate an
66 incremental search, and asked for an alternate mechanism. Bash-2.03
67 uses the value of the settable readline variable `isearch-terminators'
68 to decide which characters should terminate an incremental search. If
69 that variable has not been set, ESC and Control-J will terminate a
72 7. Some variables have been removed: MAIL_WARNING, notify, history_control,
73 command_oriented_history, glob_dot_filenames, allow_null_glob_expansion,
74 nolinks, hostname_completion_file, noclobber, no_exit_on_failed_exec, and
75 cdable_vars. Most of them are now implemented with the new `shopt'
76 builtin; others were already implemented by `set'. Here is a list of
79 MAIL_WARNING shopt mailwarn
81 history_control HISTCONTROL
82 command_oriented_history shopt cmdhist
83 glob_dot_filenames shopt dotglob
84 allow_null_glob_expansion shopt nullglob
85 nolinks set -o physical
86 hostname_completion_file HOSTFILE
87 noclobber set -o noclobber
88 no_exit_on_failed_exec shopt execfail
89 cdable_vars shopt cdable_vars
91 8. `ulimit' now sets both hard and soft limits and reports the soft limit
92 by default (when neither -H nor -S is specified). This is compatible
93 with versions of sh and ksh that implement `ulimit'. The bash-1.14
94 behavior of, for example,
102 It may be useful to define an alias:
104 alias ulimit="ulimit -S"
106 9. Bash-2.01 uses a new quoting syntax, $'...' to do ANSI-C string
107 translation. Backslash-escaped characters in ... are expanded and
108 replaced as specified by the ANSI C standard.
110 10. The sourcing of startup files has changed somewhat. This is explained
111 more completely in the INVOCATION section of the manual page.
113 A non-interactive shell not named `sh' and not in posix mode reads
114 and executes commands from the file named by $BASH_ENV. A
115 non-interactive shell started by `su' and not in posix mode will read
116 startup files. No other non-interactive shells read any startup files.
118 An interactive shell started in posix mode reads and executes commands
119 from the file named by $ENV.
121 11. The <> redirection operator was changed to conform to the POSIX.2 spec.
122 In the absence of any file descriptor specification preceding the `<>',
123 file descriptor 0 is used. In bash-1.14, this was the behavior only
124 when in POSIX mode. The bash-1.14 behavior may be obtained with
128 12. The `alias' builtin now checks for invalid options and takes a `-p'
129 option to display output in POSIX mode. If you have old aliases beginning
130 with `-' or `+', you will have to add the `--' to the alias command
133 alias -x='chmod a-x' --> alias -- -x='chmod a-x'