Re: Background processes in post-receive hook

On Sat, Apr 2, 2011 at 10:22 PM, Sitaram Chamarty <sitaramc@gmail.com> wrote:

I think that is because the hook is still reading from the command's stdout. If you close stdout/stderr, I would expect it to work. For example, the "sort" command below cannot exit until all sub-programs have finished feeding it data. You can see that despite the levels of forking involved, the stdout of perl and the stdin of sort are the same.

$ ( ( perl -e 'sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out &
[1] 4033
$ ps h
...
 4033 pts/10   S      0:00 sort
 4035 pts/10   S      0:00 perl -e sleep 60; print "THERE\n";
...
$ ll /proc/{4035,4033}/fd
/proc/4033/fd:
total 0
lr-x------ 1 jratt bgq 64 Apr  2 23:49 0 -> pipe:[55227211]
l-wx------ 1 jratt bgq 64 Apr  2 23:49 1 -> /tmp/out
lrwx------ 1 jratt bgq 64 Apr  2 23:49 2 -> /dev/pts/10

/proc/4035/fd: total 0 lr-x------ 1 jratt bgq 64 Apr 2 23:49 0 -> /dev/null l-wx------ 1 jratt bgq 64 Apr 2 23:49 1 -> pipe:[55227211] lrwx------ 1 jratt bgq 64 Apr 2 23:49 2 -> /dev/pts/10 $ cat /tmp/out $ fg ( ( perl -e 'sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out $ cat /tmp/out THERE

However, this version exits before the shell returns to the prompt (and the output is lost).

$ ( ( perl -e 'close STDOUT; close STDERR;sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out & [1] 4097 [1]+ Done ( ( perl -e 'close STDOUT; close STDERR;sleep 60; print "THERE\n";' & ) ) | sort > /tmp/out $

Joe