or download this
$ perl -MO=Deparse -walne '$;="\t";$i||=0;$h{$i,$F[0]}.="$F[1]" } cont
+inue { $i++ if eof; END{print "$_:\t" . $h{$_} for sort keys %h}' fil
+e1.txt file2.txt
BEGIN { $^W = 1; }
BEGIN { $/ = "\n"; $\ = "\n"; }
...
print "${_}:\t" . $h{$_} foreach (sort keys %h);
}
-e syntax OK