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