topic Re: ksh hangs when execute wait command in Operating System - HP-UX

ksh hangs when execute wait command

Xavier Mancho Ferreras — Tue, 15 Jul 2003 17:40:51 GMT

Hi,

I have a hanging problem inside a script when we execute a wait command after a sequence of background procesess.

Anyone know a bug on HP-UX 11.11, ksh and wait command ?

Thanks

Re: ksh hangs when execute wait command

A. Clay Stephenson — Tue, 15 Jul 2003 17:46:03 GMT

Well, the wait is supposed to "hang" until all the background tasks have completed (if no argument is supplied) or until a specified background process is finished if a PID is supplied as an argument to wait.

It would probably be helpful if you explained the problem a bit more -- and do you know that the background process(es) have finished?.

Re: ksh hangs when execute wait command

Paul Sperry — Tue, 15 Jul 2003 17:46:33 GMT

Some processes in a 2-or-more-stage pipeline may not be children of
the shell, and thus cannot be waited for.

Re: ksh hangs when execute wait command

Caesar_3 — Tue, 15 Jul 2003 17:49:51 GMT

Hello!

Explain more the problem,
add the script that we all could see and help

Caesar

Re: ksh hangs when execute wait command

Xavier Mancho Ferreras — Wed, 16 Jul 2003 06:38:40 GMT

Hi,

the script wich i have problem is:

------------------------------
cat data1 | while read valor
do
JLSC $valor &
done

wait
------------------------------

after executing and finshing all JLSC processes the script remaing 'waiting' for.

data1 is a file with a list of files to be params of JLSC.

JLSC is a short 'C' program.

Re: ksh hangs when execute wait command

Xavier Mancho Ferreras — Wed, 16 Jul 2003 06:41:21 GMT

Hi,

sorry, i forgot a important information:
this only occurs sometimes not always !

Re: ksh hangs when execute wait command

Bernhard Mueller — Wed, 16 Jul 2003 12:01:36 GMT

Quick question:

how do you generate your data1 file (i.e. your filelist)?

could it be that *sometimes* there are filesnames in it with blanks (from a Samba share or so) or some other characters that make the execution problematic?

to debug you might use set -x or
just echo the command that should be exectued to a logfile.

Regards,
Bernhard

Re: ksh hangs when execute wait command

A. Clay Stephenson — Wed, 16 Jul 2003 13:19:49 GMT

There was a subtle bug in the 11.0 ksh that was fixed but that does not apply to 11.11. I would try to run this under the POSIX shell and see if the problem persists. NOTE: In HP-UX /bin/sh (or /usr/bin/sh) is NOT the Bourne shell; it's the POSIX shell. There is really no reason to run the Korn shell because POSIX
is actually a superset of Korn and anything that you can do in the Korn shell, you can do in the POSIX shell. It would be a good thing to know if all of child processes have finished and did they spawn any processes?