How to read directory contents in Perl?

Reading directory contents in Perl is commonly done using opendir, readdir, and closedir. These built-in functions allow you to open a directory handle, read the entries, and close the handle when done.

A key point is to properly interpolate variables in strings. If you want to include a variable like $dir inside a double-quoted string, ensure the string is correctly quoted, and no conflicting quotes break your code.

Fixed runnable example

#!/usr/bin/perl
use strict;
use warnings;

# Directory to read, current directory is "."
my $dir = '.';

# Open directory handle, die on error
opendir(my $dh, $dir) or die "Cannot open directory '$dir': $!";

# Read all entries except '.' and '..'
my @files = grep { $_ ne '.' && $_ ne '..' } readdir($dh);

# Close directory handle
closedir($dh);

# Print directory contents
print "Contents of directory \"$dir\":\n";
foreach my $file (@files) {
    print "$file\n";
}

Here are some Perl-specific points:

• Sigils: The variable $dir holds the directory path. The directory handle $dh is a scalar but acts like a filehandle.
• Context: Using readdir in list context returns all entries at once, which we filter using grep.
• TMTOWTDI: You could also read entries one by one using a while loop in scalar context with readdir.

Common Pitfalls:

• Make sure strings containing variables are properly quoted. For example, use double quotes with escaped internal quotes, or use separate print arguments.
• Always check the return value of opendir and handle errors.
• Remember to exclude . and .. entries as they usually aren’t useful when listing directory content.

This example works on Perl 5.6 and later without additional modules and completes quickly without external dependencies.