Bug 981443 - wait vs. invalid pid/job spec: man page update OR wait builtin fix might be needed
wait vs. invalid pid/job spec: man page update OR wait builtin fix might be n...
Product: Fedora
Classification: Fedora
Component: bash (Show other bugs)
Unspecified Unspecified
low Severity low
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Assigned To: Siteshwar Vashisht
BaseOS QE - Apps
Depends On:
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Reported: 2013-07-04 13:54 EDT by Jan Pokorný
Modified: 2017-02-28 04:34 EST (History)
8 users (show)

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Description Jan Pokorný 2013-07-04 13:54:08 EDT
Just noticed this discrepancy man page vs. reality:

> [...]
> wait [n ...]
>        [...] the return status is zero. [...] the return status is 127.
>        Otherwise, the return status is the exit status of the last
>        process or job waited for.


> [...]
> All builtins return an exit status of 2 to indicate incorrect usage.


$ wait foo; echo $?
> -bash: wait: `foo': not a pid or valid job spec
> 1

As per man page, I would expect the above command to be instance
of incorrect usage (as no additional possibility is enumerated
at the wait description), hence would expect 2 to be the exit status.

Apparently, there is an inherent danger of exit status aliasing when
the last process or job waited for exits with 1 (or 2).
Using 2 instead of 1 would IMHO be (to limited extent) safer in this
regard, as quite common C-based program's logic is to use just
Comment 2 Roman Rakus 2013-07-09 07:15:21 EDT
Looks like all (or majority) builtins return 1 on error. Easier is to change man page. Will ask upstream.
Comment 11 Siteshwar Vashisht 2017-01-18 11:21:03 EST
I presume this can be closed with manpage update from comment 7. Is it ok with you ?
Comment 12 Jan Pokorný 2017-01-19 11:04:31 EST
Well, the expected outcome really is that wait builtin in bash won't
return 1 because of the common failure exit code aliasing issue
described in [comment 0].

Reading http://pubs.opengroup.org/onlinepubs/9699919799/utilities/wait.html
my intepretation is that it would be entirely OK if it returned 127
in case of nonsensical PID operand.

The referred man page update is no remedy here, I am afraid.
Comment 13 Siteshwar Vashisht 2017-01-31 06:58:54 EST
Moving this bug to rawhide for further discussion.
Comment 14 Fedora End Of Life 2017-02-28 04:34:17 EST
This bug appears to have been reported against 'rawhide' during the Fedora 26 development cycle.
Changing version to '26'.

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