Perl: how to access multiple directory with variables

kwoweiho · 03-05-2013, 02:17 PM

I want to access multiple directories with the following structure and concatenate all the files from each director into one file:
/a/b/c/1
/a/b/c/2
....
/a/b/c/22

Here's my code in perl:

@chr=(1 .. 22);
$n=0;
while ($chr[$n]) {
$path = "/a/b/c/$chr[$n]";
opendir(DIR, $path) or die “Cannot open $path : $!”;
system (cat * >/a/b/c/$chr[$n].txt);
closedir(DIR);
$n++;
}

there's an error in the opendir line. and maybe more, can somebody help me out please?
Thanks!
David

chrism01 · 03-05-2013, 05:43 PM

Best practice is to start code with warnings & strict turned on

Code:

#!/usr/bin/perl -w
use strict;

It would also help if you showed the error msgs you're getting.
Incidentally, you should add error handling to closedir as well.

I'd guess at least one problem is you are opening a DIR to read, but you're not changing to that dir ( chdir() ), so the cat is working in the the wrong dir.
http://perldoc.perl.org/

smallpond · 03-05-2013, 07:35 PM

First time with Perl?

I think you are confusing opendir with chdir:

Code:

use warnings;
use strict;

for my $dir (1 .. 22) {
   chdir "/a/b/c/$dir";
   system("cat * >/a/b/c/$dir.txt");
}

kwoweiho · 03-06-2013, 10:03 AM

Thanks guys, it works perfectly!