Commit fb5ef62b authored by Daniel Kahn Gillmor's avatar Daniel Kahn Gillmor

Import Upstream version 2.05b-2

parent dc36b72c
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This document details the incompatibilites between this version of bash,
bash-2.05a, 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.
Some of these incompatibilities occur between the current version and
versions 2.0 and above.
1. Bash now uses a new quoting syntax, $"...", to do locale-specific
string translation. Users who have relied on the (undocumented)
behavior of bash-1.14 will have to change their scripts. For
instance, if you are doing something like this to get the value of
a variable whose name is the value of a second variable:
eval var2=$"$var1"
you will have to change to a different syntax.
This capability is directly supported by bash-2.0:
var2=${!var1}
This alternate syntax will work portably between bash-1.14 and bash-2.0:
eval var2=\$${var1}
2. One of the bugs fixed in the YACC grammar tightens up the rules
concerning group commands ( {...} ). The `list' that composes the
body of the group command must be terminated by a newline or
semicolon. That's because the braces are reserved words, and are
recognized as such only when a reserved word is legal. This means
that while bash-1.14 accepted shell function definitions like this:
foo() { : }
bash-2.0 requires this:
foo() { :; }
This is also an issue for commands like this:
mkdir dir || { echo 'could not mkdir' ; exit 1; }
The syntax required by bash-2.0 is also accepted by bash-1.14.
3. The options to `bind' have changed to make them more consistent with
the rest of the bash builtins. If you are using `bind -d' to list
the readline keybindings in a form that can be re-read, use `bind -p'
instead. If you were using `bind -v' to list the keybindings, use
`bind -P' instead.
4. The `long' invocation options must now be prefixed by `--' instead
of `-'. (The old form is still accepted, for the time being.)
5. There was a bug in the version of readline distributed with bash-1.14
that caused it to write badly-formatted key bindings when using
`bind -d'. The only key sequences that were affected are C-\ (which
should appear as \C-\\ in a key binding) and C-" (which should appear
as \C-\"). If these key sequences appear in your inputrc, as, for
example,
"\C-\": self-insert
they will need to be changed to something like the following:
"\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-2.03
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'. Here is a list of
correspondences:
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 $ENV.
11. The <> redirection operator was changed to conform to the POSIX.2 spec.
In the absence of any file descriptor specification preceding the `<>',
file descriptor 0 is used. In bash-1.14, this was the behavior only
when in POSIX mode. The bash-1.14 behavior may be obtained with
<>filename 1>&0
12. The `alias' builtin now checks for invalid options and takes a `-p'
option to display output in POSIX mode. If you have old aliases beginning
with `-' or `+', you will have to add the `--' to the alias command
that declares them:
alias -x='chmod a-x' --> alias -- -x='chmod a-x'
13. The behavior of range specificiers within bracket matching expressions
in the pattern matcher (e.g., [A-Z]) depends on the current locale,
specifically the value of the LC_COLLATE environment variable. Setting
this variable to C or POSIX will result in the traditional ASCII behavior
for range comparisons. If the locale is set to something else, e.g.,
en_US (specified by the LANG or LC_ALL variables), collation order is
locale-dependent. For example, the en_US locale sorts the upper and
lower case letters like this:
AaBb...Zz
so a range specification like [A-Z] will match every letter except `z'.
The portable way to specify upper case letters is [:upper:] instead of
A-Z; lower case may be specified as [:lower:] instead of a-z.
Look at the manual pages for setlocale(3), strcoll(3), and, if it is
present, locale(1).
You can find your current locale information by running locale(1):
caleb.ins.cwru.edu(2)$ 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.
14. 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 ${#variable} to get the length of a variable's value.
Bash-2.x does not support it.
15. Bash no longer auto-exports the HOME, PATH, SHELL, TERM, HOSTNAME,
HOSTTYPE, MACHTYPE, or OSTYPE variables.
16. Bash no longer initializes the FUNCNAME, GROUPS, or DIRSTACK variables
to have special behavior if they appear in the initial environment.
17. Bash no longer removes the export attribute from the SSH_CLIENT or
SSH2_CLIENT variables, and no longer attempts to discover whether or
not it has been invoked by sshd in order to run the startup files.
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The version of bash in this directory has been compiled on the
following systems:
By chet:
SunOS 4.1.4
SunOS 5.5
BSDI BSD/OS 2.1
FreeBSD 2.2
NetBSD 1.2
AIX 4.2
AIX 4.1.4
HP/UX 9.05, 10.01, 10.10, 10.20
Linux 2.0.29 (libc 5.3.12)
Linux 2.0.4 (libc 5.3.12)
By other testers:
SCO ODT 2.0
SCO 3.2v5.0, 3.2v4.2
SunOS 5.3
SunOS 5.5
BSD/OS 2.1
FreeBSD 2.2
SunOS 4.1.3
Irix 5.3
Irix 6.2
Linux 2.0 (unknown distribution)
Digital OSF/1 3.2
GNU Hurd 0.1
SVR4.2
Bash POSIX Mode
===============
Starting Bash with the `--posix' command-line option or executing `set
-o posix' while Bash is running will cause Bash to conform more closely
to the POSIX 1003.2 standard by changing the behavior to match that
specified by POSIX in areas where the Bash default differs.
The following list is what's changed when `POSIX mode' is in effect:
1. When a command in the hash table no longer exists, Bash will
re-search `$PATH' to find the new location. This is also
available with `shopt -s checkhash'.
2. The message printed by the job control code and builtins when a job
exits with a non-zero status is `Done(status)'.
3. The message printed by the job control code and builtins when a job
is stopped is `Stopped(SIGNAME)', where SIGNAME is, for example,
`SIGTSTP'.
4. Reserved words may not be aliased.
5. The POSIX 1003.2 `PS1' and `PS2' expansions of `!' to the history
number and `!!' to `!' are enabled, and parameter expansion is
performed on the values of `PS1' and `PS2' regardless of the
setting of the `promptvars' option.
6. Interactive comments are enabled by default. (Bash has them on by
default anyway.)
7. The POSIX 1003.2 startup files are executed (`$ENV') rather than
the normal Bash files.
8. Tilde expansion is only performed on assignments preceding a
command name, rather than on all assignment statements on the line.
9. The default history file is `~/.sh_history' (this is the default
value of `$HISTFILE').
10. The output of `kill -l' prints all the signal names on a single
line, separated by spaces.
11. Non-interactive shells exit if FILENAME in `.' FILENAME is not
found.
12. Non-interactive shells exit if a syntax error in an arithmetic
expansion results in an invalid expression.
13. Redirection operators do not perform filename expansion on the word
in the redirection unless the shell is interactive.
14. Redirection operators do not perform word splitting on the word in
the redirection.
15. Function names must be valid shell `name's. That is, they may not
contain characters other than letters, digits, and underscores, and
may not start with a digit. Declaring a function with an invalid
name causes a fatal syntax error in non-interactive shells.
16. POSIX 1003.2 `special' builtins are found before shell functions
during command lookup.
17. If a POSIX 1003.2 special builtin returns an error status, a
non-interactive shell exits. The fatal errors are those listed in
the POSIX.2 standard, and include things like passing incorrect
options, redirection errors, variable assignment errors for
assignments preceding the command name, and so on.
18. If the `cd' builtin finds a directory to change to using
`$CDPATH', the value it assigns to the `PWD' variable does not
contain any symbolic links, as if `cd -P' had been executed.
19. If `CDPATH' is set, the `cd' builtin will not implicitly append
the current directory to it. This means that `cd' will fail if no
valid directory name can be constructed from any of the entries in
`$CDPATH', even if the a directory with the same name as the name
given as an argument to `cd' exists in the current directory.
20. A non-interactive shell exits with an error status if a variable
assignment error occurs when no command name follows the assignment
statements. A variable assignment error occurs, for example, when
trying to assign a value to a readonly variable.
21. A non-interactive shell exits with an error status if the iteration
variable in a `for' statement or the selection variable in a
`select' statement is a readonly variable.
22. Process substitution is not available.
23. Assignment statements preceding POSIX 1003.2 special builtins
persist in the shell environment after the builtin completes.
24. Assignment statements preceding shell function calls persist in the
shell environment after the function returns, as if a POSIX
special builtin command had been executed.
25. The `export' and `readonly' builtin commands display their output
in the format required by POSIX 1003.2.
26. The `trap' builtin displays signal names without the leading `SIG'.
27. The `.' and `source' builtins do not search the current directory
for the filename argument if it is not found by searching `PATH'.
28. Subshells spawned to execute command substitutions inherit the
value of the `-e' option from the parent shell. When not in POSIX
mode, Bash clears the `-e' option in such subshells.
29. Alias expansion is always enabled, even in non-interactive shells.
30. When the `set' builtin is invoked without options, it does not
display shell function names and definitions.
There is other POSIX 1003.2 behavior that Bash does not implement.
Specifically:
1. Assignment statements affect the execution environment of all
builtins, not just special ones.
2. When a subshell is created to execute a shell script with execute
permission, but without a leading `#!', Bash sets `$0' to the full
pathname of the script as found by searching `$PATH', rather than
the command as typed by the user.
3. When using `.' to source a shell script found in `$PATH', bash
checks execute permission bits rather than read permission bits,
just as if it were searching for a command.
Contents of this directory:
changelog - my change log since the last release
POSIX.NOTES - list of what changes for `posix mode'
README - this file
misc - directory with some useful tools
The following are distributed `as-is'. They will not apply without some
modification.
sh-redir-hack - diff to parse.y to get redirections before
compound commands
empty-for-wordlist - diff to parse.y to allow an empty wordlist after
the `in' keyword in a `for' statement
mh-folder-comp - diffs that reportedly add MH folder completion
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#! /bin/sh
if [ "$1" = '-y' ]; then
shift
fi
exec /usr/bin/yacc ${1+"$@"}
/*
* If necessary, link with lib/sh/libsh.a
*/
#include <stdio.h>
#include <errno.h>
extern char *strerror();
extern int sys_nerr;
int
main(c, v)