#!/usr/bin/perl -w

use strict;
use Benchmark;
use File::Find;

my @paths = (split/\:/,$ENV{PATH});

sub which1 {
        my $filename= "test.txt";
        foreach my $pathname (@paths) {
                print "$pathname/$filename\n" if ( -e "$pathname/$filename" );
        };
}

sub which2 {
        my $filename = "test.txt";
        finddepth sub {print "$_\n" if ( /$filename$/)} , @paths;
}

timethese (100, {'whichone' => \&which1, 'whichtwo' => \&which2});

##</code><code>##

[10:27:15 jhorner@gateway scripts]$ ./ch0as-1.pl test.txt
Benchmark: timing 100 iterations of whichone, whichtwo...
  whichone:  0 wallclock secs ( 0.01 usr +  0.02 sys =  0.03 CPU) @ 3333.33/s (n=100)
            (warning: too few iterations for a reliable count)
  whichtwo: 14 wallclock secs (12.54 usr +  1.55 sys = 14.09 CPU) @  7.10/s (n=100)