#!/usr/bin/perl 
 
use strict; 
use warnings; 
 
open my $features_fh, '<', 'features.txt' or die "could not open featues.txt: $!\n"; 
 
while( <$features_fh> ){ 
  if( m{ \. c \b }msx ){ 
    print "in f: $_"; 
  } 
} 
 
close $features_fh or die "could not close featues.txt: $!\n";

use strict;  
use warnings;  
while( <DATA> ){  
    (my $file_name) =  /([^\\\/]+ \. [ch]) [\s#]/xms; 
    next if !$file_name; 
    print $file_name, "\n"; 
} 
__END__ 
c:\here\there\anywhere\name.c#2    # print 'name.c' 
c:\here\there\anywhere\macro.h     # print 'macro.h' 
app.c#2                            # print 'app.c' 
script.pl#2                        # do not print 
test.h#2 
c:\here\there\anywhere\name.cxx#2  # do not print 
here/foo.html#2                    # do not print 
here/foo.h#2                       # print 'foo.h'

use strict;  
use warnings;  
open my $file2, '<', 'file2' or die 'Cannot open file2'; 
my @file_2 = <$file2>; 
close $file2; 
open my $file3, '<', 'file3' or die 'Cannot open file2'; 
my @file_3 = <$file3>; 
close $file3;  
 
open my $file1, '<', 'file1' or die 'Cannot open file2'; 
while( <$file1> ){  
    (my $file_name) =  /([^\\\/]+ \. [ch]) [\s#]/xms; 
    next if !$file_name; 
    print grep /$file_name/, (@file_2, @file_3); 
} 
close $file1;

print $file_name if grep /$file_name/, (@file_2, @file_3);

print grep /\/$file_name/, (@file_2, @file_3);

(my $file_name) =  /([^\\\/]+ \. [ch]) [\s#]/xms;  
 
Input:\ssma\products\services\utils\putlis_gsm.min;//source/modem/nas/services/rel/0987H1_200/src/putlis_gsm.min - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 2 
\ssma\products\services\utils\putlis_gsm.mak;//source/modem/nas/services/rel/0987H1_200/src/putlis_gsm.mak - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 2 
.\ssma\products\services\utils\sys_plmn_selection.c;//source/modem/nas/services/rel/0987H1_200/src/sys_plmn_selection.c - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 1 
.\ssma\products\services\utils\sys_plmn_selection.h;//source/modem/nas/services/rel/0987H1_200/inc/sys_plmn_selection.h - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 1 
 
OUTPUT: 
putlis_gsm.min 
putlis_gsm.mak 
sys_plmn_selection.c 
sys_plmn_selection.h

use strict; 
use warnings; 
while (my $line = <DATA>){ 
    (my $file_name) = $line =~ / 
        [\\\/]          # Match but do not return a slash (or backslash) 
        (               # Begin return 
            \w+         # One or more word characters (the name) 
            \.          # one period 
            \w{1,3}     # one to three word characters (extension) 
        )               # End of return 
        ;               # Match but do not return a semi-colen; 
    /xms; 
    print $file_name, "\n"; 
} 
__END__ 
\ssma\products\services\utils\putlis_gsm.min;//source/modem/nas/services/rel/0987H1_200/src/putlis_gsm.min - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 2  
\ssma\products\services\utils\putlis_gsm.mak;//source/modem/nas/services/rel/0987H1_200/src/putlis_gsm.mak - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 2 
.\ssma\products\services\utils\sys_plmn_selection.c;//source/modem/nas/services/rel/0987H1_200/src/sys_plmn_selection.c - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 1 
.\ssma\products\services\utils\sys_plmn_selection.h;//source/modem/nas/services/rel/0987H1_200/inc/sys_plmn_selection.h - VU_MIKE_ASA_SERVICES.00.00.12.00.06 : 1

use strict;   
use warnings;   
open my $file2, '<', 'file2.txt' or die 'Cannot open file2';  
my @file_2 = <$file2>;  
close $file2;  
open my $file3, '<', 'file3.txt' or die 'Cannot open file3';  
my @file_3 = <$file3>;  
close $file3;  
 
my $file = 'p4/file.ntp';  
open my $DATA, '<', $file or die "could not open '$file' $!";  
 
my %seen;   # add this before loop 
 
while (my $line = <DATA>){  
    (my $file_name) = $line =~ /  
        [\\\/]          # Match but do not return a slash (or backslash)  
        (               # Begin return  
            \w+         # One or more word characters (the name)  
            \.          # one period  
            \w{1,3}     # one to three word characters (extension)  
        )               # End of return  
        ;               # Match but do not return a semi-colen;  
    /xms;  
 
 
  (my $VU_name) = /\s(VU\w+)/xms; 
  next if (!$file_name); 
	    print $file_name, "\n";  
#      print grep /\/$file_name/, (@file_2, @file_3);  
#	 next if ((!$VU_name) or ($seen{$VU_name}++)); 
#      print "$VU_name\n"; 
#      print grep /$VU_name/, (@file_2, @file_3);  
} 
close $DATA;

Name "main::DATA" used only once: possible typo at orphan.pl line 16. 
readline() on unopened filehandle DATA at orphan.pl line 16.

 
(my $VU_name) = /\s(VU\w+)/xms;

INPUT:- 
.\msm\apps_proc\drivers\boot\ince_cache_mmu.s;//depot/asic/msmshared/apps_proc/drivers/boot/2_0/ince_cache_mmu.s - MSMSHARED_1024_SAPP_TOOL.02.00.35.01 : 2 
.\msm\build\msm\tool_debug.cmm;//depot/asic/main/build/cmm/tool_debug.cmm - VU_ROLE_TOOL_SMS_VERSION_MS.00.01.11 : 2

( my $VU_name ) = $line =~ /\-\s(\w+)/xms;