Detect empty directory with Perl - perl

Question

What is an easy way to test if a folder is empty in perl? -s, and -z are not working.
Example:
#Ensure Apps directory exists on the test PC.
if ( ! -s $gAppsDir )
{
die "\n$gAppsDir is not accessible or does not exist.\n";
}
#Ensure Apps directory exists on the test PC.
if ( ! -z $gAppsDir )
{
die "\n$gAppsDir is not accessible or does not exist.\n";
}
These above, do not work properly to tell me that the folder is empty. Thanks!
Thanks all! I ended up using:
sub is_folder_empty { my $dirname = shift; opendir(my $dh, $dirname) or die "Not a directory";
return scalar(grep { $_ ne "." && $_ ne ".." } readdir($dh)) == 0; }

Answer 1

A little verbose for clarity, but:
sub is_folder_empty {
my $dirname = shift;
opendir(my $dh, $dirname) or die "Not a directory";
return scalar(grep { $_ ne "." && $_ ne ".." } readdir($dh)) == 0;
}
Then you can do:
if (is_folder_empty($your_dir)) {
....
}

Answer 2

Using grep { ! /^[.][.]?\z/ } readdir $dir_h can be problematic for performance in case the check is done many times and some directories may have many files.
It would be better to short-circuit the moment a directory entry other than . or .. is found.
On Windows XP with ActiveState perl 5.10.1, the following sub seems to be twice as fast as the grep approach on my $HOME with 100 entries:
sub is_dir_empty {
my ($dir) = #_;
opendir my $h, $dir
or die "Cannot open directory: '$dir': $!";
while ( defined (my $entry = readdir $h) ) {
return unless $entry =~ /^[.][.]?\z/;
}
return 1;
}

Answer 3

Or without any grepping or regular expressions - which rules out any chance of weird file names accidentally getting though. Plus slightly faster is my testing.
#!/usr/bin/perl
use strict;
use warnings;
sub is_dir_empty {
return -1 if not -e $_[0]; # does not exist
return -2 if not -d $_[0]; # in not a directory
opendir my $dir, $_[0] or # likely a permissions issue
die "Can't opendir '".$_[0]."', because: $!\n";
readdir $dir;
readdir $dir;
return 0 if( readdir $dir ); # 3rd times a charm
return 1;
}
my #folders = qw( ./ ./empty ./hasonefile ./hastwofiles ./doesnotexist ./afile );
for my $folder ( #folders ) {
print "Folder '$folder' ";
my $rc = is_dir_empty( $folder );
if( $rc == -1 ) {
print "does not exist\n";
} elsif( $rc == -2 ) {
print "is not a directory\n";
} elsif( !$rc ) {
print "is not empty\n";
} else {
print "is empty\n";
}
}
Pretty simple. If you get three valid responses from a call to readdir, then you know there must be a file in there. Regardless of what name the file may have - or the order in which the files are being processed. Would have preferred something called 'is_dir_used' as I personally don't like the double-negative function name and return value.

Answer 4

There is also File::List from cpan. It's overkill here, but can be handy for slightly more complex requests like test if a directory is empty with the meaning it contains only empty directories (ie: not files).

Answer 5

Here is a more consise algorithm using Perl v5.12 (from circa 2010).
At most, three reads of the directory are made.
It does NOT read the whole directory.
It handles non-Unix filesystems that do not have '..'; See 'find' '-noleaf'
Desc: return true if empty, false if not empty; die if opendir() error
sub is_dir_empty {
use 5.012; # so readdir assigns to $_ in a lone while test
local($_); # prevent side effects
my $dir = shift // die "arg missing";
opendir my $dh, $dir or die "opendir(..,$dir): $!";
while ( readdir $dh ) {
return 0 if ! /^ [.][.]? $/x;
}
return 1;
} # is_dir_empty()

Answer 6

Credit to DevShed
if (scalar <directory/*>) {print qq|File Exists\n|}
Edit
To include hidden files:
#arr = <directory/* directory/.*>;
#arr = grep {!/^directory/[.]{1,2}$/} #arr;
if (#arr) { print qq|File or Directory Exists\n| }
Please read the comments as there have been good points made. Despite the negative points this answer has received, it is still correct.

Answer 7

opendir(DIR,"DIR PATH") or die "Unable to open directory \"DIR PATH\" \n";
my #drList = readdir(DIR);
close(DIR);
if( grep(/\w/,#drList) ){ print "Not Empty\n" }
else { print "Empty\n" }

Answer 8

sub is_folder_empty {
my $dirname = shift;
my #files = File::Find::Rule->file()->name('*')->maxdepth(1)->in("$dirname");
return $#files < 0;
}