Hi jaggu_bg,

After seeing your code with some assumptions, I have created a below script. You have to be very specific with your input and required output, so that we can give the answer without any assumptions.

I have taken input file and input string as input parameters and created the output in output.txt file.

use strict;
use warnings;

my $input_file = $ARGV[0];  #input file name
my $input_pid  = $ARGV[1];  #input file name
my $input_string = $ARGV[2];  #input string to be searched in the matc
+hed string

print "Usage: test.pl <input file name> <input process id> <input file
+ string>" if (@ARGV != 3);

open (my $hfile, '<', "$input_file") || die("Unable to open the file $
+input_file\n");

open (my $ofile, '>', "output.txt") || die("Unable to open the file ou
+tput.txt\n");

while (<$hfile>){  #read the file line by line
    
    my $line = $_;
    
    if ($line =~ /[DWEM]\s+.*?\s+(?:c|cm|M)\:($input_pid)\s+([^\.]+\.c
+)/s)    
    {
        my $c_file = $2;
        my $pid = $1;        
        
        if($input_string eq $c_file){   #check with input string and i
+f matches
            
        print $ofile "$line\n";  #write the output in a output file
            
        }        
    }    
}

Command Line:
-------------

>perl test.pl a.txt 10570 'cm_child.c'

File output.txt:
----------------
PID:10570
C File:cm_child
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Updated:Based on the input given by OP in private message and below reply