Very Computer

by **Philip Shephe** » Thu, 19 Aug 1993 14:13:22

Using ksh, I want to pipe several commands together, but be able to
determine the exit status of the first command in the pipe:

#!/usr/bin/ksh

firstcmd 2>&1 | tee /dev/console >>$logfile
exit_status=$?

if [ $exit_status = 0 ] ; then
etc...

Using the above script, exit_status is set to the exit status of "tee".
However, I'm interested in the exit status of "firstcmd"

Any ideas? I could of course spool the output of firstcmd to a temporary
file but then the console wouldn't see any error messages until "firstcmd"
exited ... not really what I want to happen.

Thanks in advance

Phil

--

University of New England
Northern Rivers
Lismore NSW Australia

by **Kjetil Torgrim Hom** » Sat, 21 Aug 1993 12:35:14

Philip Sheperd:

Quote:> Using ksh, I want to pipe several commands together, but be able to
> determine the exit status of the first command in the pipe:

Generally, I don't think this is possible without temporary files.
Ie. something like
(firstcmd; echo $? 9> /tmp/exit 1>&9) 2>&1 | secondcmd
exit_status=`cat /tmp/exit`; rm -f /tmp/exit

Quote:> firstcmd 2>&1 | tee /dev/console >>$logfile
> exit_status=$?

If we use 'tail -f' instead of 'tee' we get:

firstcmd 2>&1 >> $logfile &
firstpid=$!

tail -f $logfile & # >/dev/console if you _insist_ :-)
tailpid=$!

wait $firstpid

exit_status=$?
kill $tailpid

BTW, tee is usually used this way: '| tee $logfile' - then stdout will
be stdout.

Kjetil T.

by **David W. Tamk** » Sat, 21 Aug 1993 13:19:52

| Philip [Shepherd]:

| > firstcmd 2>&1 | tee /dev/console >>$logfile

| BTW, tee is usually used this way: '| tee $logfile' - then stdout will
| be stdout.

tee -a $logfile

Note the append redirector in Philip's example. A simple "tee $logfile"
will print to the console just fine but will clobber whatever was already
in $logfile.

David W. Tamkin Box 3284 Skokie, Illinois 60076-6284 312-714-5610

by **Philip Shephe** » Sat, 21 Aug 1993 15:21:46

My original question
:
:Using ksh, I want to pipe several commands together, but be able to
:determine the exit status of the first command in the pipe:
:
: #!/usr/bin/ksh
:
: firstcmd 2>&1 | tee /dev/console >>$logfile
: exit_status=$?
:
: if [ $exit_status = 0 ] ; then
: etc...
:
:Using the above script, exit_status is set to the exit status of "tee".
:However, I'm interested in the exit status of "firstcmd"

Quote:> Tom Christiansen has an example of doing this in the Bourne shell (and
> since the ksh is generally backwards compatible with the Bourne shell,
> it should be a solution for you too), in his "Csh considered harmful"
> paper, available via anonymous ftp from convex.com:/pub/csh.whynot.

From which I derived:

status=`(( first_command; echo $? >&3) | tee $terminal >>$logfile) 3>&1`

Thanks to jdavis for his quick response

--

University of New England
Northern Rivers
Lismore NSW Australia

Very Computer

?ksh: exit status of 1st cmd in pipe?

?ksh: exit status of 1st cmd in pipe?

?ksh: exit status of 1st cmd in pipe?

?ksh: exit status of 1st cmd in pipe?

?ksh: exit status of 1st cmd in pipe?