How could I write a Perl script to calculate the MD5 sum of every file in a directory? [closed]

Question 1

Well there are many ways to do this but it comes down to two operations you need to preform. You will first need to locate a list of the files you would like to run the check and then you will need to run the md5sum check on each of those files. There is a ton of ways to do this but the following should work for your needs.

#!/usr/bin/perl

use strict;
use warnings;
use Digest::MD5 qw(md5_hex);

my $dirname = "/home/mgreen/testing/";
opendir( DIR, $dirname );
my @files = sort ( grep { !/^\.|\.\.}$/ } readdir(DIR) );
closedir(DIR);

print "@files\n";

foreach my $file (@files) {
    if ( -d $file || !-r $file ) { next; }
    open( my $FILE, $file );
    binmode($FILE);
    print Digest::MD5->new->addfile($FILE)->hexdigest, " $file\n";
    close($FILE);
}

The above will grab the md5sum for each file in the directory and skip any sub-directories and print it to STDOUT. The MD5 checksum part is then done by the Digest::MD5 module which is ultimately what I think you are looking for.

I do like your question though as it is open-ended with alot of possible solutions like all "How do I do this in perl?" questions so I am sure you will get alot of possible solutions and I will most likely update mine when I get home later.

Question 2

Maybe using find with -exec can do the job?

find . -name "*.*" -exec md5sum '{}' \;

The '{}' will be replaced with the name of each file.

Question 3

Use opendir and readdir or other recursive method. Here is an example:

#!/usr/bin/perl -w
use warnings;
my $DIR_PATH="a";
opendir DIR, ${DIR_PATH} or die "Can not open \"$DIR_PATH\"\n";
@filelist = readdir DIR;


foreach $file (@filelist) {
  open(IN,"a/$file")or die "cannot open";
  while(<IN>){...}
  close IN;
}