Perl reading file, printing unique value from a column

Question

I am new to perl, and i\'d like to achieve the following with perl.

I have a file which contain the following data:

/dev/hda1 /boot ext3 rw          


        

Answer 1

#!/usr/bin/perl

my %hash ;
while (<>) {
if (/\s*[^\s]+\s+[^\s]+\s+([^\s]+)\s+.*/) {
    $hash{$1}=1;
}
}
print join("\n",keys(%hash))."\n";

Usage:

 ./.pl file1 fil2 ....