bin/81165: /bin/sh -e bug

[Simon Marlow]

The following reply was made to PR bin/81165; it has been noted by GNATS.

From: Simon Marlow <simonmar at gmail.com>
To: Giorgos Keramidas <keramida at ceid.upatras.gr>
Cc: bug-followup at freebsd.org
Subject: Re: bin/81165: /bin/sh -e bug
Date: Tue, 17 May 2005 21:26:34 +0100

 On 5/17/05, Giorgos Keramidas <keramida at ceid.upatras.gr> wrote:
 > On 2005-05-17 17:20, Simon Marlow <simonmar at gmail.com> wrote:
 > > There is a bug in ash's handling of the -e flag.  See the example
 > > below.
 > >
 > > $ cat >test.sh
 > > if true; then
 > >   false && true
 > > fi
 > > echo "test succeeded"
 > > $ /bin/sh -e test.sh
 > > zsh: 34546 exit 1     /bin/sh -e test.sh
 > > $ bash -e test.sh
 > > test succeeded
 > >
 > > Bash works correctly.  If the 'if' statement is removed, ash also
 > > works correctly.
 >=20
 > Are you sure what bash does is correct?  What do the standards say about
 > indermediate commands that fail and the correct behavior of the "shell"
 > (i.e. the "false" command in there)?
 
 Yes, I'm sure.  The /bin/sh manpage says:
 
      -e errexit
              Exit immediately if any untested command fails in non-interact=
 ive
              mode.  The exit status of a command is considered to be explic=
 -
              itly tested if the command is used to control an if, elif, whi=
 le,
              or until; or if the command is the left hand operand of an ``&=
 &''
              or ``||'' operator.
 
 and (clearer, IMO), the Single Unix Spec:
 
 -e
     When this option is on, if a simple command fails for any of the
 reasons listed in Consequences of Shell Errors or returns an exit
 status value >0, and is not part of the compound list following a
 while, until or if keyword, and is not a part of an AND or OR list,
 and is not a pipeline preceded by the "!" reserved word, then the
 shell will immediately exit.
 
 so the upshot is that the command
 
     false && X
 
 should not cause the script to exit when the -e switch is on (it
 doesn't matter what X is).
 
 You can easily see that the behaviour of /bin/sh is strange, because
 in this case
 
    if true; then E; fi
 
 does not behave in the same way as just E.
 
 However, it appears that /bin/sh in FreeBSD 5.3 is working correctly.
 
 Cheers,
    Simon