Summary


Although it is not the easiest language to learn, once you are comfortable using associative arrays, regular expressions, and other keys feature of Perl, you will find that it is very easy to write short but powerful scripts. It is said that Perl programs are generally shorter, easier to write, and faster to develop than corresponding C programs. They are often less buggy, more portable, and more efficient than shell scripts. According to www.perl.org, Perl is the most popular web programming language. Hopefully you now have a sense of why all this might be true.

Table 22–3 lists some of the most important Perl functions introduced in this chapter. Details about these functions, and many more, can be found in perldoc perlfuncs. Table 22–4 summarizes the special characters used in Perl scripting.

Table 22–3: Basic Perl Functions

Function

Use

print

Print a string

chomp

Remove terminal newlines

my

Declare a local variable

reverse

Reverse the order of characters in a string or elements in a list, or swap the keys and values in a hash

push, pop

Add or remove elements at the end of an array

unshift, shift

Add or remove elements at the beginning of an array

sort

Sort a list in ASCII order

keys, values

Get a list of keys or values for a hash

if, unless

Conditional statements

while, until

Loop while a condition is true (or until it becomes true)

foreach, for

Loop through the elements in a list

defined

Check whether a variable has a value other than undef

open, close

Open or close a filehandle

die

Exit with an error message

sub

Define a procedure

return

Exit from a procedure, returning a value

Table 22–4: Special Characters Used in Perl

Symbol

Use

Symbol

Use

#

comment

<>

Read input from a filehandle

$

scalar variable name

$_

Default variable

@

array name

@_

Values passed to a procedure

$#

last index in an array

//

Enclose a regular expression

%

name of a hash

!

Not

&

procedure name

&&, ||

And, or




UNIX. The Complete Reference
UNIX: The Complete Reference, Second Edition (Complete Reference Series)
ISBN: 0072263369
EAN: 2147483647
Year: 2006
Pages: 316

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