listing directories

laals · #1 (**permalink**) 02-16-06, 00:02

hi all..
i want to list all the directories in one directory(not file only directory)
means i want to open one directory and list all the directories in it
ne suggections are welcome nd helpful to me
Lal

KevinADC · #2 (**permalink**) 02-16-06, 01:22

there are a few ways to do this, here is one:

Code:

chdir('path/to/dir') or die "$!";
opendir(DIR,'.') or die "$!";
my @folders = grep { -d } readdir(DIR);
close DIR;
print "$_\n" for sort {lc$a cmp lc$b} @folders;

if you don't care about sorting the list remove the sort block:

print "$_\n" for @folders;

next time you should post any code you have already tried.

laals · #3 (**permalink**) 02-16-06, 04:09

can i tell u a truth kevin

U R SOOO GREAT!!!!!!!!!!!!!!

reneeb · #4 (**permalink**) 02-16-06, 04:26

I would recommend to avoid chdir(). This can cause Problems when you are not aware of going back.

Example:
You have this structure:

Code:

./script.pl
./test.dat
./t/dir1/
./t/dir2/
./t/dir3/

And you use this code:

Code:

chdir('./t') or die "$!";
opendir(DIR,'.') or die "$!";
my @folders = grep { -d } readdir(DIR);
close DIR;
print "$_\n" for sort {lc$a cmp lc$b} @folders;

#[...] some more code, maybe 200 lines of code

open(FILEHANDLE,"<./test.dat") or die $!;
my @lines = <FILEHANDLE>;
close FILEHANDLE;

This won't work because you are in ./t and there is no test.dat

So I would recommend to use this:

Code:

opendir(DIR,'./t') or die "$!";
my @folders = grep { -d } readdir(DIR);
close DIR;
print "$_\n" for sort {lc$a cmp lc$b} @folders;

And even better to use

Code:

use FindBin ();

...

Code:

use FindBin ();
my $dir = $FindBin::Bin . '/t';
opendir(DIR,$dir) or die "$!";
my @folders = grep { -d } readdir(DIR);
close DIR;
print "$_\n" for sort {lc$a cmp lc$b} @folders;

laals · #5 (**permalink**) 02-16-06, 06:36

hi
thnks for spending ur valuable time for me
the problem is i want to remove the . and .. directories
ne idea???????
Lals

KevinADC · #6 (**permalink**) 02-16-06, 13:41

Quote:

I would recommend to avoid chdir(). This can cause Problems when you are not aware of going back.

Well, it could be a problem if you aren't aware of going back. Many things are problems if you are unaware of something. If you want to be thoruogh:

Quote:

If there are two modules using FindBin from different directories under the same interpreter, this won't work. Since FindBin uses a BEGIN block, it'll be executed only once, and only the first caller will get it right. This is a problem under mod_perl and other persistent Perl environments, where you shouldn't use this module.

Which is why I shy away from using FIndBin

reneeb · #7 (**permalink**) 02-16-06, 20:11

Quote:

Originally Posted by laals

hi
thnks for spending ur valuable time for me
the problem is i want to remove the . and .. directories
ne idea???????
Lals

In my example...

Code:

my @folders = grep { -d $dir.'/'.$_ && $_ !~ /^\.?\.$/} readdir(DIR);

This is a regular expression. If you want more information about RegEx, you should read
perldoc perlre
perldoc perlretut
perldoc perlrequick

reneeb · #8 (**permalink**) 02-16-06, 20:15

Quote:

Originally Posted by KevinADC

Well, it could be a problem if you aren't aware of going back. Many things are problems if you are unaware of something. If you want to be thoruogh:

Which is why I shy away from using FIndBin

That's right, but I've seen even a lot of experienced programmers who did not recognize that they have used a chdir 200 lines before...

As a workaround for FindBin, you can use File::Basename and the token __FILE__....

KevinADC · #9 (**permalink**) 02-17-06, 01:59

Your solution to an easy problem of just changing back to the original directory get more complicated. But I do not want to argue the point. You raised a valid concern when you mentioned chdir() can be a problem if the programmer is unaware of changing back and that concern stands on it's own merit regardless of the work-arounds or solutions. I thank you for pointing it out.

reneeb · #10 (**permalink**) 02-17-06, 05:51

I don't want to argue as well. If you feel comfortable with chdir() and you know about possible difficulties, everything is ok. I just want that others (who never used chdir before) know the traps...

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