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Re^4: Stop Command In Perl

by monsoon (Pilgrim)
on Jul 12, 2012 at 18:40 UTC ( #981472=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Stop Command In Perl
in thread Stop Command In Perl

I think windows doesn't quite respect 'kill'. This (run on Windows 7 Professional, ActivePerl v5.12.4)

perl -e "$pid = open PIPE, '-|', 'echo one two';$/=' '; while (<PIPE>) +{ print; kill 2, $pid}"
outputs

one two

But this
perl -e "$pid = open PIPE, '-|', 'echo one two';$/=' '; while (<PIPE>) +{ print; close PIPE}"
outputs

one


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Re^5: Stop Command In Perl
by mbethke (Hermit) on Jul 12, 2012 at 22:21 UTC

    Sure, I'd expect the signal emulation in Windows to be incompatible in some way but this particular phenomenon I blame on buffering. It's very very likely that the "echo" will have finished its output before the Perl process gets scheduled again so by the time the while() starts the whole output is sitting in STDIN's buffer already. You could try spawning the Windows equivalent of "(echo one; sleep 1; echo two)" and kill()ing that.

      Tried. Still get
      one
      two
      with this
      perl -e "$pid = open PIPE, '-|', 'echo one && ping -n 5 127.0.0.1 >nul + && echo two';$/=' '; while (<PIPE>){ print $_ . \"\n\"; kill 2, $pid +}"
      Doesn't look like a buffering issue, more of a kill portability one.
        Well, in this case you'd have to leave $/ alone because there will be no spaces in your output, only newlines. There should be an extra blank line at the end of your output, right? The replies to this suggest kill 2, $pid does indeed work on Windows.

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