angshuman has asked for the wisdom of the Perl Monks concerning the following question:

I have the following piece of code to track a log-file.

I search for a pattern e.g. /Some pattern/, and come out when i get one.

open PIPE, "-|", "/usr/bin/tail", "-f", "$perf_logfile" or die "could not start 'tail' on $perf_logfile: $!";
while (<PIPE>) { if ( $_ =~ /(Some pattern)/i ) { print("- $1 encountered"); last; } } close PIPE;

This was resulting in...

/usr/bin/tail: write error: Broken pipe

/usr/bin/tail: write error

as I close the pipe, even when 'tail' is pouring its heart's content into it.

I knew the problem but decided to live with it as this was the closest best to what i wanted, with a simple implementation.

Lately i have seen it resulting in hangs in the 'close PIPE' statement; after i had a change in my workspace.

Question :

Is there a way to send CRTL-C to the /tail/ process ?

before I try and close the pipe associated with it.

Am hoping in that way i won't be seeing the hangs/errors.

Why does it work in some cases and not in another ? What does this typically depend on ?

Replies are listed 'Best First'.
Re: pipe-ing the 'tail' results in 'broken pipe'
by Anonymous Monk on Jun 17, 2013 at 08:45 UTC
    See open, perlopentut, If the "open" involved a pipe, the return value happens to be the pid of the subprocess. which means can use kill to kill it, probably :)
      That worked ! Thanks...