Never use backticks or qx() without taint mode in a program driven from the web. See perlsec.

To make your program portable, use the builtins opendir and readdir to read directories. Use File::Spec to assemble paths from directory and file. Here's a quick diff with the changes.

--- 1177457.pl    2016-12-08 12:36:42.215747438 +0100
+++ 1177457.pl.new    2016-12-08 12:45:35.603768833 +0100
@@ -2,7 +2,7 @@
 
 use strict;
 use warnings;
-
+use File::Spec;
 
 
 ### This program looks at the current directory and then makes a path
+ to all the sub directories. 
@@ -22,17 +22,20 @@
 sub list {
     my $path=$_[0]; 
     #print "DEBUG - listing [$path]\n";
-    chomp(my @files = `ls -a $path`);
+    my @files = do {
+        opendir my $dh, $path or die "opendir '$path': $!\n";
+        grep !/^\.\.?$/, readdir $dh;
+    };
     my @dirs;
     foreach(@files) { 
-        if (-d "$path/$_" && $_ ne "." && $_ ne ".."){
-              push (@dirs , "$path/$_");
-        }
+            my $f = File::Spec->catpath($path,$_);
+            push @dirs, $f if -d $f;
     }
     print "-------------------------------------\n";
     print "Generating HTML doc for path = [$path]\n";
-    open(FHOUT, ">", "$path/index.html")
-        or die "Can't open '$path/index.html':$!\n";
+        my $index = File::Spec->catpath($path,'index.html');
+    open(FHOUT, ">", $index)
+        or die "Can't open '$index':$!\n";
     print FHOUT    "<!DOCTYPE html>";
     print FHOUT    "<html><head>" 
         .    "<title>listing:</title>"

[download]

I didn't tidy the program, you have to do that yourself. There's no call to list() except in that loop whith an empty my() array -

        foreach (my @dirs) {
        &list($_);
        }

[download]

- so it doesn't produce any output but warnings (print() on unopened filehandle FHOUT).
Omit the ampersand from the call to list(). Look it up in perlsub to see what it does.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re: How to perform recursion in any OS? by shmem
in thread How to perform recursion in any OS? by rollec

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