How can I check the extension of a file using Perl?

Question

To my perl script, a file is passed as an arguement. The file can be a .txt file or a .zip file containing the .txt file.

I want to write code that looks something like this

if ($file is a zip) {

    unzip $file
    $file =~ s/zip$/txt/;
}

One way to check the extension is to do a split on . and then match the last result in the array (returned by split).

Is there some better way?

Answer 1

You can use File::Basename for this.

#!/usr/bin/perl

use 5.010;
use strict;
use warnings;

use File::Basename;

my @exts = qw(.txt .zip);

while (my $file = <DATA>) {
  chomp $file;
  my ($name, $dir, $ext) = fileparse($file, @exts);

  given ($ext) {
    when ('.txt') {
      say "$file is a text file";
    }
    when ('.zip') {
      say "$file is a zip file";
    }
    default {
      say "$file is an unknown file type";
    }
  }
}

__DATA__
file.txt
file.zip
file.pl

Running this gives:

$ ./files 
file.txt is a text file
file.zip is a zip file
file.pl is an unknown file type

Answer 2

Another solution is to make use of File::Type which determines the type of binary file.

use strict;
use warnings;

use File::Type;

my $file      = '/path/to/file.ext';
my $ft        = File::Type->new();
my $file_type = $ft->mime_type($file);

if ( $file_type eq 'application/octet-stream' ) {
    # possibly a text file
}
elsif ( $file_type eq 'application/zip' ) {
    # file is a zip archive
}

This way, you do not have to deal with missing/wrong extensions.

Answer 3

How about checking the end of the filename?

if ($file =~ /\.zip$/i) {

and then:

use strict;
use Archive::Extract;

if ($file =~ /\.zip$/i) {
    my $ae = Archive::Extract->new(archive => $file);
    my $ok = $ae->extract();
    my $files = $ae->files();
}

more information here .

Answer 4

You can check the file extension using a regex match as:

if($file =~ /\.zip$/i) {
        # $file is a zip file 
}

Answer 5

I know this question is several years old, but for anyone that comes here in the future, an easy way to break apart a file path into its constituent path, filename, basename and extension is as follows.

use File::Basename;

my $filepath = '/foo/bar.txt';

my ($basename, $parentdir, $extension) = fileparse($filepath, qr/\.[^.]*$/);
my $filename = $basename . $extension;

You can test it's results with the following.

my @test_paths = (
    '/foo/bar/fish.wibble',
    '/foo/bar/fish.',
    '/foo/bar/fish.asdf.d',
    '/foo/bar/fish.wibble.',
    '/fish.wibble',
    'fish.wibble',
);

foreach my $this_path (@test_paths) {
    print "Current path: $this_path\n";
    my ($this_basename, $parentdir, $extension) = fileparse($this_path, qr/\.[^.]*$/);
    my $this_filename = $this_basename . $extension;

    foreach my $var (qw/$parentdir $this_filename $this_basename $extension/) {
        print "$var = '" . eval($var) . "'\n";
    }

    print "\n\n";
}

Hope this helps.

Answer 6

Why rely on file extension? Just try to unzip and use appropriate exception handling:

eval {
    # try to unzip the file
};

if ($@) {
    # not a zip file
}

Answer 7

Maybe a little bit late but it could be used as an alternative reference:

sub unzip_all {
     my $director = shift;
     opendir my $DIRH, "$director" or die;
     my @files = readdir $DIRH;
     foreach my $file (@files){
              my $type = `file $director/$file`; 
              if ($type =~ m/gzip compressed data/){
                      system "gunzip $director/$file";
              }
      }       
      close $DIRH;
      return;
}

Here is possible to use linux file executing it from perl by the use of backticks (``). You area able to pass the path of your folder and evaluate if exists a file that is classified by file as gzip compressed.

Answer 8

If you do not mind using a perl module, you can use Module::Generic::File , such as:

use Module::Generic::File qw( file );
my $f = file( '/some/where/file.zip' );
if( $f->extension eq 'zip' )
{
    # do something
}

Module::Generic::File has a lot of features to handle and manipulate a file.