Hello, My corporation let go our last PERL programmer on Friday and yesterday gave me the task of finishing what he was working on. Now I am not a very accomplished PERL programmer. Pretty much I picked up a book last night and read like crazy and have been searching for an answer. The code I inherited is supposed to take two directories as ARGs and then compare them. The results of this comparison are as such: If the file exist in the Source and Destination directories then do nothing. If the file exist in the source directory and not in the destination directory then copy it to the destination. If the file exist in the destination and not in the source directory then erase it from the the destination directory. This seems pretty dern simple. The program is supposed to basically keep an internal web site updated for the employees. The problem is the following script I inherited seems to work except it only does the compare on the very last file in the hash. It load the hash up fine, but does not foreach correctly. My understanding of PERL is very weak and I know this is a poorly written piece of code. Reason enough that the person was let go. Now I am afraid same will happen to me if I don't pick PERL up fast. I am an assembly programmer that was working on embedded drivers before they moved me here. This world is a tad bit different. I included some of my own comments in the code to help with what I think is going on. If anyone has a clue and can give me a hint or help put me in the right direction it would be greatly appreciated. Perhaps I can one day come to embrace PERL (which seems like a rather powerful language.) 
#!/usr/bin/perl -w

#
# Reads contents of a directory
# in array context.
#
# Usage:
#  readdir4.pl source_directory, destination_directory
#

use File::Copy;

# remove the comment below if you want to read in the directory from a
+nd arg 
 $name1 = $ARGV[0];
 $name2 = $ARGV[1];
 

opendir(SOURCE, $name1)
             or die "Can't open $name1 due to $!";
@source_entries = readdir(SOURCE);

closedir(SOURCE);

# Lets get the destination now
         
opendir(DESTINATION, $name2)
             or die "Can't open $name2 due to $!";
             
@dest_entries = readdir(DESTINATION); 

closedir (DESTINATION);

# Sort Results.
@sourcesorted = sort(@source_entries);
@destsorted = sort (@dest_entries);

# Make a hash out of them
foreach $filename1 (@sourcesorted) {
        %hashsource = ($filename1,$filename1);
}

foreach $filename2 (@destsorted) {
        %hashdest = ($filename2,$filename2);
}

# At this point we have two sorted arrays that we can use to do compar
+es with
# The idea now is to compare Source with Destination first.
# If the file exist in Source and not in Destination then copy it over
+ to Destination
# If the file exist in both then do nothing.
# Then compare Destination with Source. If the file exist in Destinati
+on and not in source
# then erase it from Destination.

# this routine will seperate all the files into two arrays
    @union = @intersection = @difference = ();
    %count = ();
    foreach $element (@sourcesorted, @destsorted) { $count{$element}++
+ }
    foreach $element (keys %count) {
        push @union, $element;
        push @{ $count{$element} > 1 ? \@intersection : \@difference }
+, $element;
    }

# Sorting the difference array
@diffsorted = sort(@difference);
    
# Now lets compare the files. We can ignore all the files in the inter
+section list
# and compare only the files in the difference list.
# The trick is to use the @difference array correctly


foreach $filename (@diffsorted) {
        # now that we are going through each element in the @differenc
+e array lets
        # do some checking.
        # Now for every file in the sorted source list see if it is no
+t equal to a file
        # file in the differences list. If it is in the differences li
+st and it is not in the
        # source list then it should be deleted from the destination d
+irectory.
        
        unless ( exists $hashdest{$filename}){
           if ( exists $hashsource{$filename}){
           print "$filename exist in the source directory.\n";
           print "Not in the destination directory, so copy it.\n\n";
           
           #now to do actual work in here.
           chdir($name1);
           print "Now copying, $filename.\n";
           #copy($filename,$name2.$filename) or die
           #        "Can't copy $filename to $name2$filename due to $!
+.\n";
           }
           } 
           
}

foreach $filename (@diffsorted) {
        # continuation of above test. This one checks for stragglers i
+n the
        # destination directory
        
        if ( exists $hashdest{$filename}){
               unless ( exists $hashsource{$filename}) {
                  print "$filename exist in destination directory.\n";
                  print "Not in the source directory, so delete it. \n
+\n";
               # Lets change to the right directory
               # chdir($name2);
               # and delete
               unlink($name.$filename);
               print "Deleted $filename.\n";
                  }
        }
}
foreach $entry (@sourcesorted) {
        print "Source: \t$entry\n";
}

foreach $entrydest (@destsorted) {
        print "Destination: \t$entrydest\n";
}

foreach $entryinter (@intersection) {
        print "Intersection: \t$entryinter\n";
}

foreach $entrydiff (@diffsorted) {
        print "Differences: \t$entrydiff\n";
}


# readdir4.pl

[download]
Thank you for any help, Aaron Taylor

In reply to New Perl programmer looking for answer in Directory Comparisons by ATaylor

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.