#!/usr/bin/perl

exit print "Usage $0 <infile> <outfile>\n" unless $ARGV[1];

$goodshell='sh';
open(IN,"$ARGV[0]");
open(OUT,">$ARGV[1]");
while(<IN>) {
chomp;
($u,@undef)=split ':';
if (defined($goodshell)) {
if ($undef[(scalar $undef)-1]=~/$goodshell/) {
print OUT "$u:$u\n";
}
} else {
print OUT "$u:$u\n";
}
}
close(IN);
close(OUT);