Shell Programming and Scripting

787
665*5-p
5454
545-p
445-p
5454*-p

5455
787
445-p
4356
2445
144

787
445-p

$ cat file-1
787
665*5-p
5454
545-p
445-p
5454*-p
$ cat file-2
5455
787
445-p
4356
2445
144                                                                                                                                                                                                                                          
$ cat script.pl
use warnings;                                                                                                                                                                                                                                
use strict;                                                                                                                                                                                                                                  
                                                                                                                                                                                                                                             
## Check arguments.                                                                                                                                                                                                                          
die qq[Usage: perl $0 <file-1> <file-2>\n] unless @ARGV == 2;                                                                                                                                                                                
                                                                                                                                                                                                                                             
## Open both files.                                                                                                                                                                                                                          
open my $fh1, qq[<], shift @ARGV or die qq[Error: $!\n];                                                                                                                                                                                     
open my $fh2, qq[<], shift @ARGV or die qq[Error: $!\n];                                                                                                                                                                                     
                                                                                                                                                                                                                                             
## Hash to keep numbers of first processed file.                                                                                                                                                                                             
my %num;                                                                                                                                                                                                                                     
                                                                                                                                                                                                                                             
## Read first file line by line.                                                                                                                                                                                                             
while ( <$fh1> ) {                                                                                                                                                                                                                           
                                                                                                                                                                                                                                             
        ## Remove leading and trailing spaces.                                                                                                                                                                                               
        s/^\s+|\s+$//g;                                                                                                                                                                                                                       
                                                                                                                                                                                                                                             
        ## Save number in a hash.                                                                                                                                                                                                            
        $num{ $_ } = 1;                                                                                                                                                                                                                      
}                                                                                                                                                                                                                                            
                                                                                                                                                                                                                                             
## Read second file line by line.                                                                                                                                                                                                            
while ( <$fh2> ) {                                                                                                                                                                                                                           
                                                                                                                                                                                                                                             
        ## Remove leading and trailing spaces.                                                                                                                                                                                               
        s/^\s+|\s+$//g;                                                                                                                                                                                                                       
                                                                                                                                                                                                                                             
        ## If exists a hash entry means that same number was found in                                                                                                                                                                        
        ## first file, so print to output.                                                                                                                                                                                                   
        if ( exists $num{ $_ } ) {                                                                                                                                                                                                           
                printf qq[%s\n], $_;                                                                                                                                                                                                         
        }
}
$ perl script.pl file-1 file-2
787
445-p