$ cat foo
one
two
one
two
three
one
four
$ perl -anE '$h{$F[0]}++}{say qq|$_ appeared $h{$_}| for sort keys %h' foo
four appeared 1
one appeared 3
three appeared 1
two appeared 2
$ perl -v | head -3

This is perl 5, version 26, subversion 1 (v5.26.1) built for x86_64-linux-gnu-thread-multi
(with 62 registered patches, see perl -V for more detail)
$