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ccc6cda3 | 1 | This document details the incompatibilites between this version of bash, |
f73dda09 | 2 | bash-2.05a, and the previous widely-available version, bash-1.14 (which |
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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 | Some of these incompatibilities occur between the current version and |
6 | versions 2.0 and above. | |
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7 | |
8 | 1. Bash now uses a new quoting syntax, $"...", to do locale-specific | |
9 | string translation. Users who have relied on the (undocumented) | |
10 | behavior of bash-1.14 will have to change their scripts. For | |
11 | instance, if you are doing something like this to get the value of | |
12 | a variable whose name is the value of a second variable: | |
13 | ||
14 | eval var2=$"$var1" | |
15 | ||
16 | you will have to change to a different syntax. | |
17 | ||
18 | This capability is directly supported by bash-2.0: | |
19 | ||
20 | var2=${!var1} | |
21 | ||
22 | This alternate syntax will work portably between bash-1.14 and bash-2.0: | |
23 | ||
24 | eval var2=\$${var1} | |
25 | ||
26 | 2. One of the bugs fixed in the YACC grammar tightens up the rules | |
27 | concerning group commands ( {...} ). The `list' that composes the | |
28 | body of the group command must be terminated by a newline or | |
29 | semicolon. That's because the braces are reserved words, and are | |
30 | recognized as such only when a reserved word is legal. This means | |
31 | that while bash-1.14 accepted shell function definitions like this: | |
32 | ||
33 | foo() { : } | |
34 | ||
35 | bash-2.0 requires this: | |
36 | ||
37 | foo() { :; } | |
38 | ||
39 | This is also an issue for commands like this: | |
40 | ||
41 | mkdir dir || { echo 'could not mkdir' ; exit 1; } | |
42 | ||
43 | The syntax required by bash-2.0 is also accepted by bash-1.14. | |
44 | ||
45 | 3. The options to `bind' have changed to make them more consistent with | |
46 | the rest of the bash builtins. If you are using `bind -d' to list | |
47 | the readline keybindings in a form that can be re-read, use `bind -p' | |
48 | instead. If you were using `bind -v' to list the keybindings, use | |
49 | `bind -P' instead. | |
50 | ||
51 | 4. The `long' invocation options must now be prefixed by `--' instead | |
52 | of `-'. (The old form is still accepted, for the time being.) | |
53 | ||
54 | 5. There was a bug in the version of readline distributed with bash-1.14 | |
55 | that caused it to write badly-formatted key bindings when using | |
56 | `bind -d'. The only key sequences that were affected are C-\ (which | |
57 | should appear as \C-\\ in a key binding) and C-" (which should appear | |
58 | as \C-\"). If these key sequences appear in your inputrc, as, for | |
59 | example, | |
60 | ||
61 | "\C-\": self-insert | |
62 | ||
63 | they will need to be changed to something like the following: | |
64 | ||
65 | "\C-\\": self-insert | |
66 | ||
67 | 6. A number of people complained above having to use ESC to terminate an | |
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68 | incremental search, and asked for an alternate mechanism. Bash-2.03 |
69 | uses the value of the settable readline variable `isearch-terminators' | |
70 | to decide which characters should terminate an incremental search. If | |
71 | that variable has not been set, ESC and Control-J will terminate a | |
72 | search. | |
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73 | |
74 | 7. Some variables have been removed: MAIL_WARNING, notify, history_control, | |
75 | command_oriented_history, glob_dot_filenames, allow_null_glob_expansion, | |
76 | nolinks, hostname_completion_file, noclobber, no_exit_on_failed_exec, and | |
77 | cdable_vars. Most of them are now implemented with the new `shopt' | |
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78 | builtin; others were already implemented by `set'. Here is a list of |
79 | correspondences: | |
80 | ||
81 | MAIL_WARNING shopt mailwarn | |
82 | notify set -o notify | |
83 | history_control HISTCONTROL | |
84 | command_oriented_history shopt cmdhist | |
85 | glob_dot_filenames shopt dotglob | |
86 | allow_null_glob_expansion shopt nullglob | |
87 | nolinks set -o physical | |
88 | hostname_completion_file HOSTFILE | |
89 | noclobber set -o noclobber | |
90 | no_exit_on_failed_exec shopt execfail | |
91 | cdable_vars shopt cdable_vars | |
92 | ||
93 | 8. `ulimit' now sets both hard and soft limits and reports the soft limit | |
94 | by default (when neither -H nor -S is specified). This is compatible | |
95 | with versions of sh and ksh that implement `ulimit'. The bash-1.14 | |
96 | behavior of, for example, | |
97 | ||
98 | ulimit -c 0 | |
99 | ||
100 | can be obtained with | |
101 | ||
102 | ulimit -S -c 0 | |
103 | ||
104 | It may be useful to define an alias: | |
105 | ||
106 | alias ulimit="ulimit -S" | |
ccc6cda3 | 107 | |
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108 | 9. Bash-2.01 uses a new quoting syntax, $'...' to do ANSI-C string |
109 | translation. Backslash-escaped characters in ... are expanded and | |
110 | replaced as specified by the ANSI C standard. | |
111 | ||
112 | 10. The sourcing of startup files has changed somewhat. This is explained | |
113 | more completely in the INVOCATION section of the manual page. | |
114 | ||
115 | A non-interactive shell not named `sh' and not in posix mode reads | |
116 | and executes commands from the file named by $BASH_ENV. A | |
117 | non-interactive shell started by `su' and not in posix mode will read | |
118 | startup files. No other non-interactive shells read any startup files. | |
119 | ||
120 | An interactive shell started in posix mode reads and executes commands | |
121 | from the file named by $ENV. | |
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122 | |
123 | 11. The <> redirection operator was changed to conform to the POSIX.2 spec. | |
124 | In the absence of any file descriptor specification preceding the `<>', | |
125 | file descriptor 0 is used. In bash-1.14, this was the behavior only | |
126 | when in POSIX mode. The bash-1.14 behavior may be obtained with | |
127 | ||
128 | <>filename 1>&0 | |
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129 | |
130 | 12. The `alias' builtin now checks for invalid options and takes a `-p' | |
131 | option to display output in POSIX mode. If you have old aliases beginning | |
132 | with `-' or `+', you will have to add the `--' to the alias command | |
133 | that declares them: | |
134 | ||
135 | alias -x='chmod a-x' --> alias -- -x='chmod a-x' | |
28ef6c31 | 136 | |
f73dda09 | 137 | 13. The behavior of range specificiers within bracket matching expressions |
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138 | in the pattern matcher (e.g., [A-Z]) depends on the current locale, |
139 | specifically the value of the LC_COLLATE environment variable. Setting | |
140 | this variable to C or POSIX will result in the traditional ASCII behavior | |
141 | for range comparisons. If the locale is set to something else, e.g., | |
142 | en_US (specified by the LANG or LC_ALL variables), collation order is | |
143 | locale-dependent. For example, the en_US locale sorts the upper and | |
144 | lower case letters like this: | |
145 | ||
146 | AaBb...Zz | |
147 | ||
148 | so a range specification like [A-Z] will match every letter except `z'. | |
149 | ||
150 | The portable way to specify upper case letters is [:upper:] instead of | |
151 | A-Z; lower case may be specified as [:lower:] instead of a-z. | |
152 | ||
153 | Look at the manual pages for setlocale(3), strcoll(3), and, if it is | |
154 | present, locale(1). | |
155 | ||
156 | You can find your current locale information by running locale(1): | |
157 | ||
158 | caleb.ins.cwru.edu(2)$ locale | |
159 | LANG=en_US | |
160 | LC_CTYPE="en_US" | |
161 | LC_NUMERIC="en_US" | |
162 | LC_TIME="en_US" | |
163 | LC_COLLATE="en_US" | |
164 | LC_MONETARY="en_US" | |
165 | LC_MESSAGES="en_US" | |
166 | LC_ALL=en_US | |
167 | ||
168 | My advice is to put | |
169 | ||
170 | export LC_COLLATE=C | |
171 | ||
172 | into /etc/profile and inspect any shell scripts run from cron for | |
173 | constructs like [A-Z]. This will prevent things like | |
174 | ||
175 | rm [A-Z]* | |
176 | ||
177 | from removing every file in the current directory except those beginning | |
178 | with `z' and still allow individual users to change the collation order. | |
179 | Users may put the above command into their own profiles as well, of course. | |
180 | ||
f73dda09 | 181 | 14. Bash versions up to 1.14.7 included an undocumented `-l' operator to |
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182 | the `test/[' builtin. It was a unary operator that expanded to the |
183 | length of its string argument. This let you do things like | |
184 | ||
185 | test -l $variable -lt 20 | |
186 | ||
187 | for example. | |
188 | ||
189 | This was included for backwards compatibility with old versions of the | |
190 | Bourne shell, which did not provide an easy way to obtain the length of | |
191 | the value of a shell variable. | |
192 | ||
193 | This operator is not part of the POSIX standard, because one can (and | |
194 | should) use ${#variable} to get the length of a variable's value. | |
195 | Bash-2.x does not support it. | |
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196 | |
197 | 15. Bash no longer auto-exports the HOME, PATH, SHELL, TERM, HOSTNAME, | |
198 | HOSTTYPE, MACHTYPE, or OSTYPE variables. | |
199 | ||
200 | 16. Bash no longer initializes the FUNCNAME, GROUPS, or DIRSTACK variables | |
201 | to have special behavior if they appear in the initial environment. | |
202 | ||
203 | 17. Bash no longer removes the export attribute from the SSH_CLIENT or | |
204 | SSH2_CLIENT variables, and no longer attempts to discover whether or | |
205 | not it has been invoked by sshd in order to run the startup files. |