1). Use gmt (UTC) - dealing with local time and DST vs regular time is a mess. Eliminate that by only using UTC. Convert to local time only for user presentation when necessary.

2). Use a directory name format that is sortable by normal alphanumeric sort: YYYYMMDD if month is 1, then use 01. If day is 9, use 09. A date in this format can be compared and sorted against other dates using just a simple cmp instruction. Leading zeroes matter.

3). I would only use the "easily visible stuff", ie, the directory name (probably an easily parse-able part of that name). Although you are going to be creating directories on the "right dates", etc. and the -M time, etc should be the same, go with the name of the file. We want to have things that happen in the most obvious way possible and the obvious ways for users to list the files work should work. Please pay attention to (1) and (2).

I hope these 3 points will save you a lot of grief!

So, each dir name should have an easy way to parse YYYYMMDD out of it. Calculate the oldest YYYYMMDD date as a string that you want to keep. Use string compares of the regex captured date string of the file/directory name to decide whether this file/directory should be kept or not.
delete (this file/directory) if ($thisdate lt $oldestdate);

All that make sense, but if I have in this directory other directories like:


09052011
10152011
10162011
10172011
10182011
10192011
10202011
[download]

How could I compare these dates from the directory names if they are 45 days older than today's date. With the dates above I would have to delete 09052011 directory because its 45 days older than today's date.

Your date format is different from the proposed one. To make things easy, you should be using this one:

20110905
20111015
20111016
20111017
20111018
20111019
20111020
[download]

Then, just generate the string for the day 45 days ago and remove everything lesser.
How to find what that days' date was? How yould you proceed without a computer? Would you calculate the date, or just have a look into a calendar?

Hello, this is what I would do. Please see comments

#!/usr/bin/perl
use strict; 

my $older_than = 45;

# my @dirs = #could be this depending then just foreach them

my @files = </Users/somedir/*>;

foreach my $filename (@files) {
    next unless (-d $filename); # this is only letting dirs get past
    if ( int( -M $filename) > $older_than) {
        #do something
        print"dir is old:$filename\n";#print what is deleted here.
        # test what you are going to delete 
        #&erase_directory ($filename); # after test uncomment this
        #rmdir $filename; # after test uncommnet this

    }
}

sub erase_directory {
    my $directory = shift @_;
    my @files = <$directory/*>;
    foreach (@files){
        unlink "$_";
    }
}
[download]

good luck, Rob

I'm trying with something like the code below, but I am not sure on line 31  if($file <= $exp_dir_date){... because if it create directories like: 20111020 20110901 20110920, it will not delete the 20111001. Is there a better way to accomplish this?
Here is the code I am talking about:

#!/usr/bin/perl -w

use strict;
use POSIX qw(strftime);
use Date::Calc qw( Today Add_Delta_Days);


# get todays date:::
my $file_date = sprintf "%04d%02d%02d", Today();

my $current_dir = "alldir";

my $exp_dir_date = sprintf "%04d%02d%02d",Add_Delta_Days( Today(), -45
+ );

my $dir_name = strftime("%Y%m%d",localtime(time));

# when this runs, it will create a new dir in alldir directory.

unless(-e $current_dir."/".$dir_name or mkdir ($current_dir."/".$dir_n
+ame, 0755)) {
        die "Unable to create $current_dir."/".$dir_name\n";
    }

print "\n**\n";

#now open $current_dir and read its content deleting any directory old
+er than 45 days

opendir (DIR, $current_dir) or die "Couldn't open directory, $!";
while (my $file = readdir DIR)
{
  next if $file=~/^\./;
  if($file <= $exp_dir_date){
    
    print "\nDELETE:::$file - $file_date - $exp_dir_date\n\n";
    rmdir("alldir/$file"); #-------> remove directory 
  }else{
    
    print "\nOK:::$file* = $file_date - $exp_dir_date\n\n";      
  
  }
}
closedir DIR;

print "\n\ndone\n";
[download]

Give this a try

#!/usr/bin/perl
use strict;
use POSIX qw(strftime);
use Date::Calc qw( Today Add_Delta_Days);

my $older_than = 45;


# get todays date:::
my $file_date = sprintf "%04d%02d%02d", Today();

my $current_dir = "alldir";

my $exp_dir_date = sprintf "%04d%02d%02d",Add_Delta_Days( Today(), -45
+ );

my $dir_name = strftime("%Y%m%d",localtime(time));

# when this runs, it will create a new dir in alldir directory.

unless(-e $current_dir."/".$dir_name or mkdir ($current_dir."/".$dir_n
+ame, 0755)) {
        die "Unable to create $current_dir."/".$dir_name\n";
    }

print "\n**\n";

#now open $current_dir and read its content deleting any directory old
+er than 45 days

my @files = </$current_dir/*>;

foreach my $filename (@files) {
    next unless (-d $filename); # this is only letting dirs get past
    if ( int( -M $filename) > $older_than) {
        print"dir is old:$filename\n";#print what is deleted here.
        # test what you are going to delete 
        #&erase_directory ($filename); # after test uncomment this
        #rmdir $filename; # after test uncommnet this

    }
}

sub erase_directory {
    my $directory = shift @_;
    my @files = <$directory/*>;
    foreach (@files){
        unlink "$_";
    }
}
[download]

Good luck, Rob