There's a module that does exactly what you're looking for, it's called File::Find. It allows you to traverse a file tree, and (should you so desire) perform operations based upon each file you come across.

Here's some code that demonstrates how to use File::Find to find and print the location of .pl files.

use File::Find;

find(\&printer, "/path/to/dir");

sub printer {
    print "I have found $File::Find::name\n" if /\.pl$/;
}
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use File::Find

find(
    sub {print "I have found $File::Find::name\n" if /\.pl$/;},
    "/path/to/dir");
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Hope you find this useful.

Cheers,
Paul

Thanks, and ditto to busunsl. That's certainly solved the problem - I can write my script now, and have re-learnt the ever valuable lesson that time spent researching CPAN is rarely time wasted. But I'd still be very interested if anyone can shed light on why my own attempt didn't work. Is the while loop not restarting? And if so why not?

§ George Sherston

If this runs on Unix, it might be you are hitting the '.' directory.

You would be looping on that till eternity.

Your question is, why didn't this work?

The answer is that while(glob("*/")) has the glob working in its scalar context mode, which returns one directory element at a time. The problem is that when you pop into a subdirectory and pop back up again the iterator for the glob starts all over again at the beginning of the directory. I just noticed, you do this twice in the program. You wind up stepping on both iterators each subdirectory you go down.

Get the entire glob list out all at once into an array (which is localized to the sub) and then iterate over that. Try something like this (untested):

sub
GetDirs
{
    my ($Dir, $Posn) = @_;
    chdir $Dir if $Dir;
    my @list=glob("*/");
    foreach (@list) {
        print "<div style=\"margin-left:$Posn\">$_</div>";
        &GetDirs($_, $Posn + $Indent);
    }
    my @exts=glob("*.$ext");
    foreach (@exts) {
        print "<div style=\"margin-left:$Posn\"><a href=\"editor.pl?Ac
+tion=GetScript&File=$_\" target=\"$_\">$_</a><BR>";
    }
    chdir "../" if $Dir;
}
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I absolutely agree with the other posters and I think that File::Find is the solution.

However if you want to fix your program keep a couple of things in mind: check if you're following symlinks and get the list at once evaluating <glob> in a list context instead of scalar context, for it might be confusing when mixed with recursion. You always use <*/> and if perl uses some sort of caching, in a scalar context, even in a deeper level of recursion, you'd get a file from the previous list of globbed files!

And symbolic links can lead you to infinite recursion as well.

To clarify with an example, I found out that this script is easily fooled by symlinks and even if there aren't any it goes into infinite recursion:

#!/usr/bin/perl -w

use strict;

sub do_list {
        my($level, $base_path) = @_;
        my @list;

#       @list = <$base_path/*>;
#       for (@list) {
        while(<$base_path/*>) {
                print '>' x $level, ' ';
                print "$_\n";
                next if -l $_;
                if(-d "$_") {
                        do_list($level + 1, $_)
                }
        }
        $level--;
}

do_list(1, $ARGV[0] || '.');
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Now, just get rid of the while and use the assignment and the for loop instead: evaluating the glob in list context prevents interferences between recursion and the "next" value returned by the "right" glob expression.

-- TMTOWTDI

.
.
local $_; # always a good habit unless you know why don't want it
chdir $Dir;
opendir DIR, '.';
my (@dirs, @files);
for (readdir DIR) {
    next if /^\.\.?$/; # we don't want to catch the . and .. entries
    push @dirs, $_ if -d and not -l; # only non-symlink dirs please
    push @files, $_ if -f and /\.ext$/; # -f because it could be a dir
+ectory or other non-file called "something.$ext"
}
closedir DIR;
.
.
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