Perl network programming cheat sheet

perldoc perltoc

Perl documentation Table of Contents (ToC)

perldoc perlfunc

List of built-in Perl functions

perldoc perlop

List of Perl operators and precedence

perldoc perllocal

Locally installed modules list (if any)

Greater than

>

gt

Greater than or equal

>=

ge

Inequality

!=

ne

C-style Logical AND operator

&&

($a && $b) is false

C-style Logical OR operator

||

($a || $b) is true

C-style Logical NOT operator

!

!($a) is false

Double-quotes - Interpolated data enclosing

$bar = "it is worth $foo";

it is worth 5

Without quotes

$bar = q(it is 'worth' $foo);

$bar = qq(it is "worth" $foo);

it is 'worth' $foo
it is "worth" 5

left

->

Infix dereference operator

--

Auto-decrement.

right

\

Reference to an object (unary).

right

+ -

Unary plus, minus.

left

! ~

Same, but negates the result.

left

+ - .

Addition, subtraction, concatenation

named unary operators

E.g. sin, chdir, -f, -M.

== != <=>

eq ne cmp

Numerical equal, not equal, compare.

Stringwise equal, not equal, compare.

Compare operators return -1 (less), 0 (equal)

or 1 (greater).

left

| ˆ

Bitwise OR, exclusive OR.

left

||

Logical OR.

right

? :

Conditional (if ? then : else) operator.

left

,

Comma operator, also list element separator.

list operators (rightward)

See below.

left

and

Low precedence logical AND.

-0[octal/hexadecimal]

Specifies the input record separator ($/ ) as an octal or hexadecimal number

-c

Causes Perl to check the syntax of the program and then exit without executing it

-d, -dt

Runs the program under the Perl debugger

-e commandline

May be used to enter one line of program

-f

Disable executing $Config{sitelib}/sitecustomize.pl at startup

-h

Prints summary if the options

-M

-Mmodule executes use module ; before executing your program

-p

Input loop in the script with line printing

-T

Turns on taint so you can test

-V

Prints summary of the major perl configuration values and the current values of @INC

-xdirectory

Tells Perl that the program is embedded in a larger chunk of unrelated text

$

Default variable

$\

The output record separator for the print operator

$)

The effective GID (Group ID) of this process

$`

The string preceding whatever was matched by the last successful pattern match

$ARGV

Contains the name of the current file when reading from <>

%ENV

The hash %ENV contains your current environment

@INC

Contains the list of places that the do EXPR , require, or use constructs look for their library files

$^

The name of the current top-of-page format for the currently selected output channel

$^L

What formats output as a form feed. The default is \f

$^X

The name used to execute the current copy of Perl

$@

The Perl error from the last eval operator, i.e. the last exception that was caught

$.

Current line number for the last filehandle accessed.

$=

The current page length (printable lines) of the currently selected output channel. The default is 60

$|

If set to nonzero, forces a flush right away and after every write or print on the currently selected output channel

$+

The text matched by the highest used capture group of the last successful search pattern

-e

Single line of script

-c

Checks syntax

-p

Printing an input loop

-M

Load a module

-v

Version and patch level of script

\

reference

{ }

hashref

$var

Default variable

$p = \@var

Now $p is a reference to @var

$var[-1]

Last element of array @var

$var{’JAN’}

A value from ‘hash’ %var

$$p{’JAN’}

A value from hash referenced by $p

@var

The entire array

@var{’X’,’Y’}

A slice of %var; same as ($var{’X’},$var{’Y’})

$var{’a’,1,...}

Emulates a multidimensional array;

@arr = (1..3);

Array initialization

@arr = split(­/-/­,$text);

Split the string into $text

$arr = pop(@arr);

Removes the last element in the array

Special variables

@ARGV array which stores all the command line arguments

@ENV hash of program’s environment

Server-side Method

Server-side Socket Script Example

Client-side Method

Client-side Socket Script Example

abs

Absolute value

bind

Binds an address to a socket

chdir

Change current working directory

chop

Remove the last character from a string

close

Close file

connect

Connect to a remote socket

delete

Deletes a value from a hash

dump

Create a core dump immediately

eval

Compile and run code

exp

Exponential

gethostbyaddr

Get host record IP address

getlogin

Return who is logged in at this TTY

getnetent

Get next networks record

getprotobyname

Get protocol record given name

getprotoent

Get next protocols record

getpwnam

Get passwd record given user login name

getservbyname

Get services record given its name

getservent

Get next services record

getsockopt

Get socket options on a given socket

join

Join a list into a string using a separator

length

Return the number of bytes in a string

m

Match a string with a regular expression pattern

msgrcv

Receive a SysV IPC message from a message queue

my

Declare and assign a local variable (lexical scoping)

print

Output a list to a filehandle

push

Append one or more elements to an array

qq

Doubly quote a string

quotemeta

Quote regular expression magic characters

qx

Backquote quote a string

read

Fixed-length buffered input from a filehandle

readline

Fetch a record from a file

recv

Receive a message via a Socket

return

Exit function early

send

Send a message via a socket

shutdown

Terminate half of the socket connection

sort

Sort a list of values

syscall

Execute an arbitrary system call