A ksh bug on "wait"

Nov 9, 2009

WTF?

$ cat kshbug
{ return 0; } &
evil=$(/bin/true)   # XXX: works fine without this line
wait $!
echo $?

$ ksh kshbug
127

$ ksh --version
version         sh (AT&T Labs Research) 1993-12-28 r

The correct return code should be 0. Without the line of “eval=$(bin/true)” everything works fine. The problem happens only when

  1. Execute a function or a clause in background, and
  2. A subshell is invoked between the background execution and the “wait”, and
  3. An external command is executed in the subshell

I googled for a while, there’s no ksh bug report so far, workaround could be use output text for return code check instead. Note there’s a similar report for ksh on solaris but it’s not the identical issue.

Pdksh (public domain ksh) doesn’t have the problem. (See another bug).

Couldn’t figure out where to report this bug so gave up.

Update: this issue doesn’t happen on Ubuntu ksh version sh (AT&T Research) 93s+ 2008-01-31.

#ksh