Hello PerlMonks,
Please help me with the following problem..

My goal is to fill a file - called testfile with data by cat'ing /dev/urandom so I have written the following code it. I just want to fill the file for about 1 second and then I want to kill the process. 

#!/usr/bin/perl
use warnings;
use strict;

if (-f "./testfile")
{
!system "rm -f testfile" or die "Couldn't delete already present
testfile\n";
}
my $pid;
my $parent = $$;
open (INFILE, "+>testfile") or die "Can't create testfile: $!";
print "This is parent $parent \n";
defined($pid = fork) or die "Cannot fork: $!";
unless($pid)
{
# Child process is here
print "This is child pid $$\n";
exec "cat /dev/urandom > testfile";
}
sleep 1;
close INFILE;
kill -9 => $pid;

[download]
When exec is executed here actually two processes are created and though it baffled me initially I realized there were actually two things going on in the exec call; one is the cat /dev/urandom and the second I believe is the shell is being invoked to carry out the redirection. So the output of the program is as follows 
# ./test.pl
This is parent 29307
This is child pid 29309
#

[download]
Now even after the prgram finishes execution (that is I get the prompt back), the testfile is still being populated from the output of /dev/urandom. This should not happen. and a ps -ef gives the following 

# ps -ef|grep urandom
root 29309 1 0 00:53 pts/2 00:00:00 sh -c cat /dev/urandom >
testfile
root 29310 29309 99 00:53 pts/2 00:00:12 cat /dev/urandom

[download]
My questions:
1. When I kill the process process 29310 testfile stops growing, but how do I get that to happen from within the code?
2. Why does process 29309 still show when I have killed it in my code?

Thanks in Advance,
Santosh

In reply to exec creates two processes.. how to kill them? by santosh_sugur

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