How to copy a file in Perl?

How to Copy a File in Perl

Copying a file in Perl is commonly done using the core module File::Copy, which provides a straightforward and reliable copy function. However, to successfully copy a file, the source file must exist before the copy operation; otherwise, you will get errors like No such file or directory.

This example demonstrates how to safely copy a file by first creating a sample source file in-memory. This approach avoids external dependencies, works perfectly in a sandbox, and shows the complete workflow.

Key Points About Perl's File Copying

• File::Copy::copy returns true on success, false on failure.
• Source and destination file names are scalars, denoted by $ (scalar sigil).
• Always check the return value of copy and I/O operations to handle errors gracefully.
• Use binmode on filehandles if copying binary files (important on Windows).
• Perl emphasizes “There’s more than one way to do it” (TMTOWTDI), but File::Copy is usually simplest.

Runnable Example: Copying a File Successfully

use strict;
use warnings;
use File::Copy;

my $source = 'example_source.txt';
my $destination = 'example_copy.txt';

# Create a source file to copy
open my $src_fh, '>', $source or die "Can't create $source: $!";
print $src_fh "Sample content for copying.\n";
close $src_fh;

# Copy the file
if (copy($source, $destination)) {
    print "Successfully copied '$source' to '$destination'.\n";
} else {
    die "Copy failed: $!";
}

# Read and print the destination file to verify
open my $dst_fh, '<', $destination or die "Can't open $destination: $!";
print "Contents of '$destination':\n";
print while <$dst_fh>;
close $dst_fh;

This script:

• Creates example_source.txt with sample text.
• Copies it to example_copy.txt using File::Copy::copy.
• Prints confirmation or dies on error.
• Reads back the destination file and prints its contents to STDOUT.

Common Pitfalls and Notes

• Missing source file: If the source file does not exist, copy will fail with an error.
• Binary files: Use binmode on filehandles when copying binary files manually.
• Permissions: The copy function preserves file content but not extended metadata like timestamps.
• Filehandles and buffers: When copying manually, buffer sizes and error checking are important to avoid silent data loss.

Using File::Copy is the recommended way to copy files in Perl for clarity, safety, and portability. Just ensure the source file exists beforehand to avoid runtime errors.