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ccc6cda3 | 1 | This document details the incompatibilites between this version of bash, |
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2 | bash-2.03, 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. | |
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5 | |
6 | 1. Bash now uses a new quoting syntax, $"...", to do locale-specific | |
7 | string translation. Users who have relied on the (undocumented) | |
8 | behavior of bash-1.14 will have to change their scripts. For | |
9 | instance, if you are doing something like this to get the value of | |
10 | a variable whose name is the value of a second variable: | |
11 | ||
12 | eval var2=$"$var1" | |
13 | ||
14 | you will have to change to a different syntax. | |
15 | ||
16 | This capability is directly supported by bash-2.0: | |
17 | ||
18 | var2=${!var1} | |
19 | ||
20 | This alternate syntax will work portably between bash-1.14 and bash-2.0: | |
21 | ||
22 | eval var2=\$${var1} | |
23 | ||
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: | |
30 | ||
31 | foo() { : } | |
32 | ||
33 | bash-2.0 requires this: | |
34 | ||
35 | foo() { :; } | |
36 | ||
37 | This is also an issue for commands like this: | |
38 | ||
39 | mkdir dir || { echo 'could not mkdir' ; exit 1; } | |
40 | ||
41 | The syntax required by bash-2.0 is also accepted by bash-1.14. | |
42 | ||
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 | |
47 | `bind -P' instead. | |
48 | ||
49 | 4. The `long' invocation options must now be prefixed by `--' instead | |
50 | of `-'. (The old form is still accepted, for the time being.) | |
51 | ||
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 | |
57 | example, | |
58 | ||
59 | "\C-\": self-insert | |
60 | ||
61 | they will need to be changed to something like the following: | |
62 | ||
63 | "\C-\\": self-insert | |
64 | ||
65 | 6. A number of people complained above having to use ESC to terminate an | |
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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 | |
70 | search. | |
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71 | |
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' | |
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76 | builtin; others were already implemented by `set'. Here is a list of |
77 | correspondences: | |
78 | ||
79 | MAIL_WARNING shopt mailwarn | |
80 | notify set -o notify | |
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 | |
90 | ||
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, | |
95 | ||
96 | ulimit -c 0 | |
97 | ||
98 | can be obtained with | |
99 | ||
100 | ulimit -S -c 0 | |
101 | ||
102 | It may be useful to define an alias: | |
103 | ||
104 | alias ulimit="ulimit -S" | |
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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. | |
109 | ||
110 | 10. The sourcing of startup files has changed somewhat. This is explained | |
111 | more completely in the INVOCATION section of the manual page. | |
112 | ||
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. | |
117 | ||
118 | An interactive shell started in posix mode reads and executes commands | |
119 | from the file named by $ENV. | |
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120 | |
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 | |
125 | ||
126 | <>filename 1>&0 |