jesuashok has asked for the wisdom of the Perl Monks concerning the following question:

Hi All - Sincere apologies if this has been asked before and I am repeating. Just needed a quick input from experts here. May I know what I am doing wrong in below code. For some reason, the directories are not being processed recursively. I do see that the program finds a directory and the function is being called recursively. But, only one time it is being called and not working as expected. 
#!/usr/bin/perl

my $parent_dir = "/panther/home/efxprod/support";

process_dir($parent_dir);

sub process_dir {
        my $dir = shift;
        print "Processing $dir\n";
        opendir(SCR , $dir) or die "Can't open $dir: $!";
        while( defined ($file = readdir SCR) )
        {
           next if ($file =~ /\.$/ );
           next if ($file =~ /\.txt$/ );
           if ( $file =~ /\.sh$/ ) {
             print "not a regullar file: $file\n";
           } elsif ( $file =~ /\.pl$/) {
             print "perl $file\n";
           } elsif ( -d "$dir/$file" ) {
             print "directory : $file\n";
             process_dir("$dir/$file/");
             #next;
           #} elsif ( $file
           } else {
                print "Else :$file\n" if ( -B "$dir/$file");
           }
           print "file -> $file\n";
        }
    return;
}

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Replies are listed 'Best First'.
Re: Require input reading files recursively in perl
by CountOrlok (Friar) on Apr 17, 2013 at 13:22 UTC
    General disclaimer: use strict/warnings.

    Using a global filehandle (or in general any global variable that can be modified) with recursion is a *bad* idea. Instead use lexcials: 
    opendir(my $SCR , $dir) or die "Can't open $dir: $!";
while( defined (my $file = readdir $SCR) )

    [download]
    Don't forget to closedir when done.
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[d/l]
      Thanks a lot. Below is the newer version and it works fine. Appreciate the time and your valuable input. 
      #!/usr/bin/perl

use strict;
use warnings;

my $parent_dir = "/panther/home/efxprod/support";

process_dir($parent_dir);

sub process_dir {
        my $dir = shift;
        print "Processing $dir\n";
        opendir(my $SCR , $dir) or die "Can't open $dir: $!";
        while( defined (my $file = readdir $SCR) )
        {
           next if ($file =~ /\.$/ );
           next if ($file =~ /\.txt$/ );
           if ( $file =~ /\.sh$/ ) {
             print "not a regullar file: $file\n";
           } elsif ( $file =~ /\.pl$/) {
             print "perl $file\n";
           } elsif ( -d "$dir/$file" ) {
             print "directory : $dir/$file\n";
             process_dir("$dir/$file/");
             #next;
           #} elsif ( $file
           } else {
                print "Else :$file\n" if ( -B "$dir/$file");
           }
           print "file -> $file\n";
        }
    closedir($SCR);
}

      [download]
[reply]
[d/l]
Re: Require input reading files recursively in perl
by kcott (Archbishop) on Apr 17, 2013 at 13:19 UTC

    G'day jesuashok,

    How about you add these lines to your code and let Perl tell you what's wrong: 

    use strict;
use warnings;

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    strict should tell you about $file in while( defined ($file = readdir SCR) ) which, I believe, is your immediate problem.

    warnings may pick up something I haven't spotted.

    Please endeavour to add these two lines to all your scripts.

    -- Ken

[reply]
[d/l]
[select]
      This standard chunk of cargo-cult programming won't actually fix the OP's problem, since the global SCR directory handle will still get overwritten. A dose of "local" or "my" will fix it, and an explanation of what is happening would lead to the right solution.
      Just another Perler interested in Algol Programming.
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Re: Require input reading files recursively in perl
by hdb (Monsignor) on Apr 17, 2013 at 13:12 UTC

    If you do _not_ want to do the recursion yourself, you also could use File::Find .

    UPDATE: added "not"

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Re: Require input reading files recursively in perl
by choroba (Cardinal) on Apr 17, 2013 at 13:09 UTC
    readdir returns file names, not paths. To really access the file (as in opendir), you have to prepend the path to the file name.

    Update: My comment is irrelevant to the problem. I was not able read the code properly because it was placed in the signature part of the post which renders without syntax highlighting and other bells and whistles I am accustomed to.

    لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ
[reply]


      As you can see from above code, when I call the function recursively, I am passing arguments by doing pre-pend the directory name so that the opendir would know what the directory it should open. Did I get that wrong? Feel free to correct.
[reply]

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