From: Peter Stephenson <pws@csr.com>
To: zsh-workers@sunsite.dk (Zsh hackers list)
Subject: Minor wait behaviour thing
Date: Thu, 27 Sep 2001 10:33:47 +0100 [thread overview]
Message-ID: <8360.1001583227@csr.com> (raw)
I'm not sure if this is even worth remarking on...
Here's a trivial script to start four jobs in the background and wait for
all four to finish.
sleep 10 &
pid1=$!
echo Job 1 started, pid $pid1
sleep 15 &
pid2=$!
echo Job 2 started, pid $pid2
sleep 5 &
pid3=$!
echo Job 3 started, pid $pid3
sleep 20 &
pid4=$!
echo Job 4 started, pid $pid4
wait $pid1
echo Job 1 finished
wait $pid2
echo Job 2 finished
wait $pid3
echo Job 3 finished
wait $pid4
echo Job 4 finished
As you can see, job 3 will finish before jobs 1 and 2. Since the PID isn't
stored --- we don't know how long we'd have to keep it, so it would just
clutter up the shell --- the wait skips it. However, it prints out a
message; here's the complete sequence:
Job 1 started, pid 8330
Job 2 started, pid 8331
Job 3 started, pid 8332
Job 4 started, pid 8333
Job 1 finished
Job 2 finished
./wait4:wait:25: pid 8332 is not a child of this shell
Job 3 finished
Job 4 finished
which is, at that point, correct, but confusing. sh and ksh don't print a
message. I wonder if it's more trouble than it's worth?
--
Peter Stephenson <pws@csr.com> Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK Tel: +44 (0)1223 392070
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reply other threads:[~2001-09-27 9:34 UTC|newest]
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