Roland,
I did confirm this interpretation with Don Cragun, and he agrees.
ksh93 (and the Solaris standard shell /usr/xpg4/bin/sh) would need to return 0
in the case of unsetting a variable which is not set, to
conform with the standard.
I guess you could also interpret the
> 0 exit value for "at least one name could not be unset"
to not be true in this case. The name was unset already, so the result
is still that the name is unset. Therefore, unset was successful.
Thanks,
April
> Date: Fri, 09 Jan 2009 23:36:26 +0100
> From: Roland Mainz <roland.mainz at nrubsig.org>
> X-Accept-Language: en
> To: April Chin <April.Chin at eng.sun.com>, OpenSolaris Shell discussions
<shell-discuss at opensolaris.org>, ksh93-integration-discuss
<ksh93-integration-discuss at opensolaris.org>, David Korn <dgk at
research.att.com>
> Subject: Re: CR 6791838 Created P3 shell/korn93 *ksh93* unset of a
variablewhich is not set should return 0
> X-Virus-Scanned: ClamAV 0.94.1/8848/Fri Jan 9 14:16:38 2009 on
mail-in-11.arcor-online.net
> X-Virus-Status: Clean
>
> bugmail-sender at Sun.COM wrote:
> >
> > *Synopsis*: *ksh93* unset of a variable which is not set should return 0
> >
> >
> > *Change Request ID*: 6791838
> >
> > *Synopsis*: *ksh93* unset of a variable which is not set should return 0
> >
> > Product: solaris
> > Category: shell
> > Subcategory: korn93
> > Type: Defect
> > Subtype: Functionality
> > Status: 5-Cause Known
> > Substatus:
> > Priority: 3-Medium
> > Introduced In Release:
> > Introduced In Build:
> > Responsible Engineer: <User 1-5Q-5151>
> > Keywords:
> >
> > === *Description*
============================================================
> > In ksh93, the special builtin "unset" will exit 1 when its argument is a
> > variable which is not set, but it should exit 0, according to the POSIX
standards.
>
> Erm... I interpret the standard a bit different in this case:
> http://www.opengroup.org/onlinepubs/000095399/utilities/unset.html says:
> -- snip --
> EXIT STATUS
>
> 0
> All name operands were successfully unset.
> >0
> At least one name could not be unset.
> -- snip --
>
> Both ksh88, ksh93 and /usr/xpg4/bin/sh in Solaris behave like this:
> -- snip --
> $ /usr/xpg4/bin/sh -c 'unset kjashdjkashd || print "unset returned
> non-zero exit code"'
> unset returned non-zero exit code
> $ ksh -c 'unset kjashdjkashd || print "unset returned non-zero exit
> code"'
> unset returned non-zero exit code
> $ ksh93 -c 'unset kjashdjkashd || print "unset returned non-zero exit
> code"'
> unset returned non-zero exit code
> -- snip --
>
> Don: Is there any clarification request which defined the behaviour of
> "unset" more precisely ?
>
> ----
>
> Bye,
> Roland
>
> --
> __ . . __
> (o.\ \/ /.o) roland.mainz at nrubsig.org
> \__\/\/__/ MPEG specialist, C&&JAVA&&Sun&&Unix programmer
> /O /==\ O\ TEL +49 641 3992797
> (;O/ \/ \O;)
