I would have gone with an iteratively-built list, FWIW, and avoided the overhead in parsing fields the script won't use: perl -e 'for $i (<>) { $i =~ s/ .*

I would have gone with an iteratively-built list, FWIW, and avoided the overhead in parsing fields the script won't use: perl -e 'for $i (<>) { $i =~ s/ .*//; push @list, $i; }; print(sort(@list));'