Two very usefull functions to have around.

(note: dollarfy requires commify to work)

Software Requirements:

Crypt_HMAC:
http://pear.php.net/package/Crypt_HMAC
HTTP_REQUEST:
http://pear.php.net/package/HTTP_Request
PEAR:
http://pear.php.net/

Checks to see if a file or folder exists
The fFile variable determines whether you're
looking for a File (True) or Folder(False)
The strName variable holds the fully qualified
path you're looking For

this function returns the aggregated size
of all files in a directory and its subdirectories

Retrieve information about a file

Check the attributes of a file or folde

A function that will either read a file or read a string, and parse a random line from it. Very simple.

Is this file the same as that file? The files may or may not be binary. We could compare the modify dates, or the sizes. But, those are not very accurate to know if a file has really changed.

Introducing MD5 Checksum. We can feed the files into Digest::MD5 in binary mode.

This is a great way to do Incremental Backups.

This is also an easy way to verify checksums when downloading files from the internet which list their MD5 Checksums.

You'll need the Digest::MD5 Perl Module.

Need to GZip a file using Perl?

Use Compress::Zlib.

This is a simple perl script which creates a GZip file.

This function loads an File into an String.