in reply to Comparing each line of a file to itself

Hello, Manju Moorthy, and welcome to the Monastery.

You could do this in Perl but is there any need when

$ sort file | uniq -c

would seem to be all you require? Just for fun here's a Perl equivalent

$ perl -ne '$x{$_}++;END {printf ("%5i %s", $x{$_}, $_) for keys %x};' file

In Section Seekers of Perl Wisdom