• Type: Variables are either scalars prefixed by $, arrays of scalars prefixed by @, or hashes of scalar pairs prefixed by %.

• Operators: same as Java except eq, gt, lt, … for string comparisons.

• Control Structures (selection and iteration): same as Java plus foreach for hashes.

• Cool stuff: interpolation, here-docs, regex, and web goodies such as param and %ENV.

Default file handlers:

• STDIN: Standard input from console
• STDOUT: Standard output to console
• STDERR: Standard error output to console

Opening a file

open(FILEHANDLE, filename)

Where FILEHANDLE specifes the name for the file handler in which you will refer to your file and filename specifies the location of your file.

In the file name one can specify the various read/write modes.

File locking for I/O is provided using the flock() function. It is suggested to do the lock on a seperate file to prevent race conditions.

open(LOCK, ">write.lock")
flock(LOCK, LOCK_EX);
open(DATA, myFile);
#...do work with the DATA file...
close LOCK;
close DATA;

Closing the LOCK handler automatically unlocks the semaphore. One can also use flock(LOCK, LOCK_UN) to do the unlocking specifically. The flock function takes the following operation parameters: