Consider the following example. There I used setpgrp to make the process group and process group id as forked process

check.pl 
print "process id: $$\n";
my $pid = fork;
my $FH;
unless($pid){
    setpgrp;
    exec('script');
}
print "Child process id is: $pid\n";
while(1) {sleep(5)}

[download]
script file: 
use POSIX;

while(1) {
    sleep(1);
    print "I am running\n";
    my $pid = fork;
    unless($pid)
    {
       while(1) {  sleep(2);
                   print "I am child and I'am running\n";
       }
    }
}

[download]

In the script file once again fork the process and printing the line

From another terminal using kill -9 <Negative number of the child process id> command kill all the process belongs to this process group

The child process is running as a defunct process but the parent process is alive

Refer the ps command output
643 15141 9607 0 18:14 pts/1 00:00:00 perl check.pl
643 15142 15141 0 18:14 pts/1 00:00:00 script <defunct>

How could I avoid this problem

Also I need to redirect the script command output and error into one file . How can I achieve it?

In reply to Re^6: Obtain the child process id in perl by Anonymous Monk
in thread Obtain the child process id in perl by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.