How to check if a file exists and is readable in Perl

Perl provides file test operators for checking file properties before operations:

use strict;
use warnings;

my $filename = 'data.txt';

# Check if file exists
if (-e $filename) {
    print "File exists\n";
}

# Check if file exists and is readable
if (-r $filename) {
    print "File is readable\n";
}

# Check if file exists and is writable
if (-w $filename) {
    print "File is writable\n";
}

# Check if it's a regular file (not directory)
if (-f $filename) {
    print "Is a regular file\n";
}

# Check if it's a directory
if (-d $filename) {
    print "Is a directory\n";
}

# Get file size
if (-s $filename) {
    my $size = -s $filename;
    print "File size: $size bytes\n";
}

# Combining tests (stacked operators)
if (-f $filename && -r $filename && -s $filename) {
    print "File exists, is readable, and not empty\n";
}

# Common pattern
open my $fh, '<', $filename or die "Cannot open $filename: $!";

Common operators: -e (exists), -f (file), -d (directory), -r (readable), -w (writable), -x (executable), -s (size), -z (zero size).