Perl for Web Site Management

Finding Files with File::Find

The first step in building our first link checker is to figure out a way for our script to get a list of all the HTML files on our site. Back in Chapter 4, we fed our script a list of filenames on the command line using the shell’s ability to expand wildcard characters. Now, though, we’re going to take a different approach, by using the standard File::Find module. We use it by putting use File::Find into our script, then invoking the module’s find function. This will make it easy to construct a script that processes all the files under a given starting directory, including those in deeper subdirectories.

We’ll start with the simple demonstration script, find_files.plx , shown in Example 11-1. (Like all the examples in this book, you can download it from the book’s web site, at http://www.elanus.net/book/.)

Example 11-1. find_files.plx

#!/usr/bin/perl -w

# find_files.plx

# this script demonstrates the use of the File::Find module.

use strict;
use File::Find;

my $start_dir = shift
    or die "Usage: $0 <start_dir>\n";

unless (-d $start_dir) {
    die "Start directory '$start_dir' is not a directory.\n";
}

find(\&process, $start_dir);

sub process {

    # this is invoked by File::Find's find function for each
    # file it recursively finds.

    print "Found $File::Find::name\n";
}

Most of this script should look pretty straightforward at this point. It starts off by shifting off the first item in @ARGV (that is, the first argument supplied to the script when it was invoked ...