execute a command using OPEN

kaka_2 has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks,

I want to execute a command using open which is using "|" inside it. Sample command is "ls -ltr /tmp | wc -l".

i wrote the simple codes as below.

#!/usr/bin/perl
use warnings;
my $cmd = "ls -ltr | wc -l";
open (CCCC, "$cmd |") || die "Failed: $! \n";
close CCCC;
[download]

and now i get a exception "Broken pipe". Can someone help me with it.

Comment on execute a command using OPEN Download Code

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Re: execute a command using OPEN by zentara (Cardinal) on Sep 10, 2014 at 14:48 UTC
I don't get your broken pipe error, I get nothing. What I think you are failing to do is actually read the CCCC filehandle. This works: `#!/usr/bin/perl use warnings; use strict; use IPC::Open3; my $pid = open3(0, \READ, 0,"ls -ltr \| wc -l"); #if \ERROR is false, STDERR is sent to STDOUT #get the answer chomp(my $answer = <READ>); print "query = $answer\n"; waitpid($pid, 1); # It is important to waitpid on your child process, # otherwise zombies could be created.` [download] I'm not really a human, but I play one on earth. Old Perl Programmer Haiku ................... flash japh	[reply] [d/l]
Re: execute a command using OPEN by ikegami (Patriarch) on Sep 10, 2014 at 15:25 UTC
That error originates from the shell as a result of `wc` being killed by SIGPIPE when it tries to write to its output handle after you closed it in your program. If you were to actually read `wc`'s output, you wouldn't have this problem.	[reply] [d/l] [select]
Re: execute a command using OPEN (broken pipe) by tye (Sage) on Sep 10, 2014 at 14:48 UTC
Read from the CCCC handle that you opened (to the end of the stream). - tye	[reply]
Re: execute a command using OPEN by parv (Parson) on Sep 10, 2014 at 14:44 UTC
None such problem here.	[reply]