"Real 
programmers put lots of useful comments in their programs."

pointers in perl -> $$p[28] 29th element of array referenced by $p. Also: $p->[28]. 

Perl rules of object oriented programming: 
An object is simply a reference that happens to know which class it belongs to. 
Objects are blessed, references are not. 
A class is simply a package that happens to provide methods to deal with object 
references. 
If a package fails to provide a method, the base classes as listed in @ISA are 
searched. 
A method is simply a subroutine that expects an object reference (or a package 
name, for static methods) as the first argument. 
Methods can be applied with: 
METHOD OBJREF PARAMETERS or 
OBJREF->METHOD PARAMETERS 

sed in perl - [ $VAR = ̃ ] s/PATTERN/REPLACEMENT/ [ e g i m o s x ] 

he following filename conventions apply when opening a file. 
"FILE" open FILE for input. Also "<FILE". 
">FILE" open FILE for output, creating it if necessary. 
">>FILE" open FILE in append mode. 
"+<FILE" open existing FILE with read/write access. 
"+>FILE" create new FILE with read/write access. 
"+>>FILE" read/write access in append mode. 

passwd 
Returns ($name, $passwd, $uid, $gid, $quota, $comment, $gcos, $dir, $shell). 
endpwent Ends look-up processing. 
getpwent Gets next user information. 
getpwnam NAME Gets information by name. 
getpwuid UID Gets information by user ID. 
setpwent Resets look-up processing.