bin/77067: /bin/sh premature termination when 'set -e' is active

Brian Candler B.Candler at
Thu Feb 3 07:50:23 PST 2005

>Number:         77067
>Category:       bin
>Synopsis:       /bin/sh premature termination when 'set -e' is active
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Feb 03 15:50:16 GMT 2005
>Originator:     Brian Candler
>Release:        FreeBSD 5.3-STABLE i386
System: FreeBSD 5.3-STABLE FreeBSD 5.3-STABLE #0: Mon Dec 27 12:24:34 GMT 2004 root at i386


Under certain circumstances, 'set -e' causes /bin/sh to exit when it should
not. From the manpage:

     -e errexit
             Exit immediately if any untested command fails in non-interactive
             mode.  The exit status of a command is considered to be explic-
             itly tested if the command is used to control an if, elif, while,
             or until; or if the command is the left hand operand of an `&&''
             or `||'' operator.

However, there are circumstances where even when a command status is
explicitly tested the script still terminates. I can replicate this using a
function call.


This script demonstrates the problem:


set -e

foo ( ) {
  if test "x$1" != "xyes"; then
    return 1
  echo "OK!"   # this line causes the problem!

if foo yes; then echo "yes"; fi
if foo no; then echo "no"; fi
echo "Completed!"

It fails to complete. However, if you remove the 'echo "OK!"' line it *does*
complete. (This line can be anything - for example, replacing it with
"return 0" also causes the problem).

The script runs correctly under 'bash', so I don't think my understanding of
-e semantics is broken.



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