Postinstall script errors

Matthias Andree matthias.andree@gmx.de
Thu Aug 12 14:52:00 GMT 2010


Am 12.08.2010 16:40, schrieb Corinna Vinschen:
> On Aug 12 16:10, Matthias Andree wrote:
>> Am 12.08.2010 15:37, schrieb Jeremy Ramer:
>> > I verified that $created_passwd and $created_group were both no so
>> > both conditionals will fail. But because the last conditional is the
>> > last thing run, the script returns 1.  Adding an exit 0 to the script
>> > fixes it, but I'm not sure if that accomplishes what you want from the
>> > script.
>> 
>> PLEASE DON'T.
>> 
>> Adding an "exit 0" will mask the error and just reinstate the former state of
>> silently failing postinstall scripts more rigidly. This is not desirable. The
>> proper way to fix this is:
>> 
>> set -e  # this is providing that the whole script is written properly.
>>         # it causes immediate exit after one command (outside if, and
>>         # outside || or && lists) fails - usually desirable, but takes more
>>         # work because you can't write the scripts as sloppily as the
>>         # snippet you've just shown from passwd-grp.sh.
>> #
>> # ...other work...
>> #
>> if [ "$created_passwd" = "yes" ] ; then
>> 	/bin/chgrp --silent root /etc/passwd
>> fi
>> 
>> if [ "$created_group" = "yes"  ] ; then
>> 	/bin/chgrp --silent root /etc/group
>> fi
> 
> I misinterpreted the `chgrp --silent'.  I thought it would result
> in an exit code of 0 from chgrp, but it just suppresses the error
> messages.  Sorry about that.

And you're missing the other point that I've just explained on cygwin-apps@, see
http://www.cygwin.com/ml/cygwin-apps/2010-08/msg00116.html

"[ $blah = foo ] && ..."   is usually suspicious and often triggers bogus
failures or premature exit, depends on if running under set +e (default) or set
-e (advised).

-- 
Matthias Andree

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