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 matched 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 output.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 if 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