cheetsheetz/perl.md

Perl Cheat Sheet

Basics

Comments

# This is a comment

Print

print "Hello, World!\n";

Variables

$scalar_variable = 42;
@array_variable  = (1, 2, 3);
%hash_variable   = ('key' => 'value');

Control Structures

if-else

if ($condition) {
    # Code to execute if condition is true
} else {
    # Code to execute if condition is false
}

foreach

foreach $item (@array) {
    # Code to execute for each item in the array
}

while

while ($condition) {
    # Code to execute while condition is true
}

Subroutines

sub greet {
    my $name = shift;
    print "Hello, $name!\n";
}

greet("Alice");

Regular Expressions

Matching

if ($string =~ /pattern/) {
    # Code to execute if pattern is found in $string
}

Substitution

$string =~ s/find/replace/;

File Handling

Open and Read

open(my $file, '<', 'filename.txt') or die "Can't open file: $!";
while (<$file>) {
    chomp;
    print "$_\n";
}
close($file);

Open and Write

open(my $file, '>', 'output.txt') or die "Can't open file: $!";
print $file "Hello, File!\n";
close($file);

Modules

Using Modules

use Module::Name;

Exporting Functions

use Module::Name qw(function1 function2);

References

Scalar Reference

$scalar_ref = \$scalar_variable;

Array Reference

$array_ref = \@array_variable;

Hash Reference

$hash_ref = \%hash_variable;

Advanced Perl Cheat Sheet

Basics

Comments

# This is a comment

Print

print "Hello, World!\n";

Variables

$scalar_variable = 42;
@array_variable  = (1, 2, 3);
%hash_variable   = ('key' => 'value');

Data Types

$string = "Perl";
$number = 42;
$float  = 3.14;

Control Structures

if-else

if ($condition) {
    # Code to execute if condition is true
} elsif ($another_condition) {
    # Code to execute if another condition is true
} else {
    # Code to execute if all conditions are false
}

foreach

foreach $item (@array) {
    # Code to execute for each item in the array
}

while

while ($condition) {
    # Code to execute while condition is true
}

Subroutines

sub greet {
    my $name = shift;
    print "Hello, $name!\n";
}

greet("Alice");

Returning Values

sub add {
    my ($num1, $num2) = @_;
    return $num1 + $num2;
}

my $result = add(3, 4);
print "Sum: $result\n";

Regular Expressions

Matching

if ($string =~ /pattern/) {
    # Code to execute if pattern is found in $string
}

Substitution

$string =~ s/find/replace/;

File Handling

Open and Read

open(my $file, '<', 'filename.txt') or die "Can't open file: $!";
while (<$file>) {
    chomp;
    print "$_\n";
}
close($file);

Open and Write

open(my $file, '>', 'output.txt') or die "Can't open file: $!";
print $file "Hello, File!\n";
close($file);

Modules

Using Modules

use Module::Name;

Exporting Functions

use Module::Name qw(function1 function2);

References

Scalar Reference

$scalar_ref = \$scalar_variable;

Array Reference

$array_ref = \@array_variable;

Hash Reference

$hash_ref = \%hash_variable;

Structuring a Perl Script for Bash

Create a Perl Script

#!/usr/bin/perl
use strict;
use warnings;

# Perl script code here
print "Hello from Perl!\n";

Make it Executable

chmod +x script.pl

Run from Bash

./script.pl