Package: bash
Version: 3.1dfsg-9
Severity: minor
In the SHELL GRAMMAR section, the bash man page first describes
(simple) commands and pipeplines, then lists:
A list is a sequence of one or more pipelines separated by one of
^^^^^^^^^
the operators ;, &, &&, or ||, and optionally terminated by one
of ;, &, or <newline>.
but a few lines later, it talks about commands instead of pipelines:
[...] An AND list has the form
command1 && command2
command2 is executed if, and only if, command1 returns an exit
status of zero.
An OR list has the form
command1 || command2
command2 is executed if and only if command1 returns a non-zero
exit status. The return status of AND and OR lists is the exit
status of the last command executed in the list.
Also, though the man page says that && and || have equal precedence,
it doesn't say which associativity. For instance, is it
(1) list && pipeline
or
(2) pipeline && list
? For instance, in
pipeline1 || pipeline2 && pipeline3
where pipeline1 returns 0 (true) and pipeline2 returns 1 (false):
Case 1: list "pipeline1 || pipeline2" is executed. As pipeline1 is
true, pipeline2 is not executed. And as the list is true, pipeline3
is executed.
Case 2: pipeline1 is executed, and as it is true, the list
"pipeline2 && pipeline3" is not executed, i.e. neither pipeline2,
nor pipeline3.
It seems to be Case 1 (left associative):
$ true || false && echo case1
case1
So, I suppose that the above should be replaced by:
[...] An AND list has the form
list && pipeline
pipeline is executed if and only if list returns an exit status of
zero.
An OR list has the form
list || pipeline
pipeline is executed if and only if list returns a non-zero exit
status. The return status of AND and OR lists is the exit status
of the last pipeline executed in the list.
-- System Information:
Debian Release: lenny/sid
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 2.6.24.3-20080226 (SMP w/2 CPU cores; PREEMPT)
Locale: LANG=POSIX, LC_CTYPE=en_US.ISO8859-1 (charmap=ISO-8859-1)
Shell: /bin/sh linked to /bin/bash
Versions of packages bash depends on:
ii base-files 4.0.2 Debian base system miscellaneous f
ii debianutils 2.28.4 Miscellaneous utilities specific t
ii libc6 2.7-9 GNU C Library: Shared libraries
ii libncurses5 5.6+20080203-1 Shared libraries for terminal hand
Versions of packages bash recommends:
pn bash-completion <none> (no description available)
-- no debconf information
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