Re^3: How to know the status of a command invoked by open function?

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why the following two opens have different result?

open(PS,"ls . 2>/dev/null |")
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is equivalent to

open(PS, '-|', /bin/sh', '-c', 'ls . 2>/dev/null ')
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but

open(PS,"ls . |")
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get optimised to

open(PS, '-|', 'ls', '.')
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Also see the update to my original reply.

But how can i get the exit status for the command in this case?

You already know how. It's in $? after a successful close. In this case, it's 141. The shell returns 141 (128|SIGPIPE) when its child dies from SIGPIPE.

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Re^4: How to know the status of a command invoked by open function? by zhujian0805 (Sexton) on Aug 16, 2011 at 01:21 UTC
it's weird that i get return code '0' when i run my script on AIX.	[reply]
Re^5: How to know the status of a command invoked by open function? by ikegami (Patriarch) on Aug 16, 2011 at 01:42 UTC
Yes, very weird. You'd get zero if `ls` managed to finish before `close` closed the pipe, but that's not very likely. Or maybe AIX processes in general or AIX's `ls` specifically behave differently when they encounter a closed pipe. Or maybe the shell doesn't relay the death of the child to its parent in AIX. On AIX, what output do you get from `/bin/sh -c 'perl -e'\''kill TERM => $$'\''' ; echo $?` [download]	[reply] [d/l] [select]
Re^6: How to know the status of a command invoked by open function? by zhujian0805 (Sexton) on Aug 16, 2011 at 01:56 UTC
`# /bin/sh -c 'perl -e'\''kill TERM => $$'\''' ; echo $? Terminated 143` [download]	[reply] [d/l]
Re^7: How to know the status of a command invoked by open function? by ikegami (Patriarch) on Aug 16, 2011 at 02:39 UTC