--- Begin Message ---
- To: Debian Bug Tracking System <submit@bugs.debian.org>
- Subject: bash: doesn't handle suspension of commands in conditional lists correctly
- From: Branden Robinson <branden@debian.org>
- Date: Sun, 02 Jan 2005 20:54:31 -0500
- Message-id: <20050103015431.4A21A68C055@sisyphus.deadbeast.net>
Package: bash
Version: 3.0-12
Severity: important
Things like:
foo && bar && baz
are a basic POSIX shell feature, and Bash doesn't handle them right.
Try:
echo one && sleep 10 && echo two
While, in the sleep, background the command with CTRL-Z.
The 'echo two' will run immediately. This is wrong. The sleep has no exit
status yet because it has not exited, and the && and || connectives must
only be evaluated once the preceding command has exited. Until then, the
command in question *has* no exit status. The box with Schroedinger's Cat
in it has not yet been opened.
ash, dash, pdksh, and zsh are also buggy, but instead they never run "echo
two" at all. It appears that of Debian's allegedly POSIX-compliant shells
have this problem, except for posh.
Here are some speculations/argument from #debian-devel as to what may be
going on:
08:42PM|<asuffield> Overfiend: what you have in bash is bloody broken
conditionals. I can't see how to fix it, and I can't stand looking
at bash any longer to figure it out
08:42PM|<asuffield> it passes WUNTRACED to wait() when job control is
enabled, so that it can spot jobs which have been sent SIGSTOP
08:43PM|<asuffield> somewhere in the pipeline logic is a missing check
for WIFSTOPPED on the status code, to see if the process is really
dead yet or not
08:49PM|<asuffield> look, WSTOPCODE() and WEXITCODE() are the same
macro. zsh is calling WEXITCODE() and treating it as the exit code,
and this is *INCORRECT*, because WIFEXITED() is false and WIFSTOPPED()
is true
08:51PM|<Keybuk> and zsh documents that it won't continue a pipeline if
the process is terminated by an unhandled signal
08:52PM|<Keybuk> so zsh is being correct, just different to bash
08:52PM|<asuffield> zsh has incorrectly interpreted the result from wait()
as if the process had been terminated
08:52PM|<asuffield> the process has been stopped. this is a different
event
-- System Information:
Debian Release: 3.1
APT prefers unstable
APT policy: (500, 'unstable'), (500, 'testing')
Architecture: powerpc (ppc)
Kernel: Linux 2.4.25-powerpc-smp
Locale: LANG=C, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Versions of packages bash depends on:
ii base-files 3.1.2 Debian base system miscellaneous f
ii libc6 2.3.2.ds1-20 GNU C Library: Shared libraries an
ii libncurses5 5.4-4 Shared libraries for terminal hand
ii passwd 1:4.0.3-30.7 Change and administer password and
-- no debconf information
--- End Message ---
--- Begin Message ---
- To: 288322-done@bugs.debian.org
- Subject: pdksh: doesn't handle suspension of commands in conditional lists correctly
- From: Thorsten Glaser <tg@mirbsd.de>
- Date: Wed, 27 Jun 2012 11:03:54 +0000 (UTC)
- Message-id: <Pine.BSM.4.64L.1206271103120.3110@herc.mirbsd.org>
Hi,
thanks Dieter for the explanation. I also think this is not
user-friendly, but it’s kept at upstream as feature request
for now.
bye,
//mirabilos
--
13:37⎜«Natureshadow» Deep inside, I hate mirabilos. I mean, he's a good
guy. But he's always right! In every fsckin' situation, he's right. Even
with his deeply perverted taste in software and borked ambition towards
broken OSes - in the end, he's damn right about it :(! […] works in mksh
--- End Message ---