From: Vincent Lefevre <vincent@vinc17.net>
To: zsh-users@zsh.org
Subject: process substitution bug with set -e?
Date: Mon, 14 Oct 2013 14:41:27 +0200 [thread overview]
Message-ID: <20131014124126.GA31070@ypig.lip.ens-lyon.fr> (raw)
The zshexpn(1) man page of zsh 5.0.2 says:
There is an additional problem with >(process); when this is attached
to an external command, the parent shell does not wait for process to
finish and hence an immediately following command cannot rely on the
results being complete. The problem and solution are the same as
described in the section MULTIOS in zshmisc(1). Hence in a simplified
version of the example above:
paste <(cut -f1 file1) <(cut -f3 file2) > >(process)
(note that no MULTIOS are involved), process will be run asynchronously
as far as the parent shell is concerned. The workaround is:
{ paste <(cut -f1 file1) <(cut -f3 file2) } > >(process)
The extra processes here are spawned from the parent shell which will
wait for their completion.
Now, consider the following script:
#!/usr/bin/env zsh
set -e
{ /bin/cp } 2>>(sleep 1; cat -n)
Due to /bin/cp failure and the "set -e", the parent shell exits
immediately, without waiting for the extra processes:
ypig% ./zsh-procsubst
ypig% 1 /bin/cp: missing file operand
2 Try '/bin/cp --help' for more information.
(tested under Debian/unstable).
Shouldn't the parent shell wait in this case?
If this is the expected behavior, the man page should be fixed,
and possibly give another workaround in the case of set -e.
--
Vincent Lefèvre <vincent@vinc17.net> - Web: <http://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
next reply other threads:[~2013-10-14 12:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-14 12:41 Vincent Lefevre [this message]
2013-10-14 13:48 ` Peter Stephenson
2013-10-14 15:08 ` Vincent Lefevre
2013-10-14 16:23 ` Bart Schaefer
2013-10-14 16:28 ` Peter Stephenson
2013-10-14 17:47 ` Bart Schaefer
2013-10-15 8:42 ` Peter Stephenson
2013-10-15 14:29 ` Bart Schaefer
2013-10-16 17:53 ` Peter Stephenson
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