You snuck in the tests like "-z _". This is completely correct usage. As extra explanation for the OP, a file test operation is actually a fairly "expensive" file system operation. See: File:stat. When doing multiple tests on the same file, for the first, test the file name. This causes a structure with all kinds of stuff to be returned from the file system. For the 2nd, 3rd, etc. tests, use "_" instead of the file name and this enables Perl to return cached info based upon the last big stat request from the file system - meaning that these subsequent tests go a lot faster.

About cwd.. It is not clear what the OP intends to do on files that pass "whatever the file test(s) are". I strive to do minimal processing within the File::find wanted routine. The reason is that File::find will cwd down the directory structure as it goes about its business. If it "blows up" because maybe some complicated "process a .pdf file" routine blows up which got called from within File::find, you will be left in some random place in the file structure far removed from whatever directory the script started in. That can complicate recovery error procedures. So usually I just generate a "to-do" list within the file find procedure and then do the actual complicated work once all the files have been found. Now of course there are a lot of "yeah, buts" to that general approach. Mileage certainly does vary! I am just saying that in my experience, keeping the "wanted routine" simple is a good idea.

Update: The OP wrote: After much searching and reading, the articles I have have found regarding File::Find do nothing other than list file names, though they begin by saying things such as "do something with file". In general, I would make an array, my @found; Have the "wanted" routine push applicable $File:find:name onto that array and then process those files once File::find has finished its job. Keeping the "wanted" routine simple and restricting its job to just "finding files" to operate upon can save a lot of grief.

G'day Marshall,

"Ken, I like your code!"

Thanks. I appreciate the compliment.

'You snuck in the tests like "-z _".'

Unfortunately, the OP gave very little information about Perl experience or, indeed, File::Find usage requirements. As this was a first post, I didn't make a big deal about it; although, I did provide a link "for information on how you can help us to help you".

My main aim was to provide the requested "help or a tutorial". I did consider including an explanation for the special filehandle, '_'; however, as I didn't know if these tests would be used, I chose to add a link to that information. I did use the link text "file tests", in case "-X" was too cryptic. :-)

"About cwd"

The last paragraph of my post did include a warning about specifying directories; an explanation that I'd only used Cwd for my example code; and, suggested a number of better alternatives. Furthermore, I only used the getcwd() function to generate the required @directories_to_search for find(); there was no explicit changing of directories in my script.

Of course, there is the implicit changing of directories as part of File::Find's default behaviour. You can change that: see "File::Find - %options - no_chdir".

Your comments regarding using an array are sound. You may actually want to use the list more than once. I assume you know how to do this, but for the OP or anybody else, here's a very basic (partial) code example:

...
find(\&wanted, @dirs);
do_something_with(get_found_files());
check_something_done_with(get_found_files());
...
{
    my @found_files;

    sub get_found_files { return @found_files }

    sub wanted {
        ...
        push @found_files, $File::Find::name;
        ...
    }
}
[download]

Note that the anonymous block makes @found_files (lexically) private: only get_found_files() and wanted() have access to it. You can, of course, modify the list returned, but the original will stay intact. For anyone unfamiliar with this concept, see "perlsub: Private Variables via my()" for a more in-depth discussion of this topic.

— Ken

Hi kcott!

Yes, my reply to your post was meant to be a compliment.

I have no idea of what the OP is trying to accomplish. There is a huge amount that is left unsaid.

As a very simple example, I present this code (create found, populate found, do something with found):

#!/usr/bin/perl
use strict;
use warnings;

use File::Find;

# lists all "normal files" which are both readable and
# writeable underneath "C:/test"

my @found;

find( { wanted => \&get_files }, "C:/test" );

print "$_\n" for @found;


sub get_files 
{  
   return unless ( -f $File::Find::name and -r _ and -w _);
   
   push @found, $File::Find::name;
}        

__END__
printed on my machine:
Note that the sub directory of "subdirtest" is skipped.
A directory name fails the -f test.

C:/test/maur-1110.tiff 
C:/test/maur-1111.psd 
C:/test/TUMI-1354839054_alt1_.psd 
C:/test/subdirtest/docinbsubdir.txt 
C:/test/subdirtest/New Text Document.txt
[download]

> I strive to do minimal processing within the File::find wanted routine

So do I! I find I grow fewer grey hairs that way. ;) To illustrate, here's a simple example of using File::Find to find all .txt files under the current working directory.

use strict;
use warnings;
use Cwd;
use File::Find;

# Return a list of the absolute path of all plain .txt files under $di
+r
sub FindTextFiles
{
   my $dir = shift;
   my @files;
   # Note: -f = plain file (perldoc -f -X for doco of all file tests)
   find( { no_chdir => 1,
           wanted   => sub { -f && /\.txt$/ and push @files, $File::Fi
+nd::name }
         },
         $dir
   );
   return @files;
}

my $dir = getcwd();
my @txtfiles = FindTextFiles($dir);
print "Found ", scalar(@txtfiles), " text files under dir '$dir'...\n"
+;
for my $file (@txtfiles) {
   print "file='$file'\n";
   # could add code to modify the found files here ...
}
[download]

Example output of running this program:

Found 5 text files under dir 'C:/pm/file-find'...
file='C:/pm/file-find/example.txt'
file='C:/pm/file-find/fred/f1/zz.txt'
file='C:/pm/file-find/fred/f2/hello.txt'
file='C:/pm/file-find/fred/f2/f2a/2a.txt'
file='C:/pm/file-find/fred/f2/f2a/hello.txt'
[download]

Once I've built the list of files, I sometimes set about changing them in-place -- which is surprisingly tricky to do robustly, as described at Re-runnably editing a file in place (see also CPAN File::Replace by haukex, which nicely solves this problem).

A practice exercise for the OP: extend the test program above to change all occurrences of Peking to Beijing in the .txt files (which I sometimes torture job applicants with :).