#!/usr/bin/perl -w
use strict;
my %locations;
foreach my $path (split(/:/,$ENV{PATH})) {
  opendir(DIR,$path) 
    || die "Directory $path in your PATH can not be opened:$!\n";
  foreach my $file (readdir(DIR)) {
    next if -d "$path/$file"; # not sure if this is really needed...
    next unless -x _;
    push (@{$locations{$file}},$path);
  }
}

foreach my $file (sort keys %locations) {
  print "$file :",join(" ",@{$locations{$file}}),"\n" 
    if scalar($#{$locations{$file}});
}