Apache webserver 

#  list loaded modules

/usr/sbin/apache2ctl -M

# list avaiable modules

apachectl -t -D DUMP_MODULES

# check config

apache2ctl -S

a2dismod status - disable module

apachectl -V

# enable default SSL site

a2ensite default-ssl

# disable default SSL site

a2dissite default-ssl

htaccess
http://www.panticz.de/apache-htaccess

Enable mod_rewrite module

sudo a2enmod rewrite
cat < /etc/apache2/conf-available/allow-override.conf

AllowOverride all

EOF

a2enconf allow-override

service apache2 reload

Graceful restart
apachectl -k graceful

# /etc/apache2/sites-available/default f

change"AllowOverride None" to "AllowOverride All"
or the directory in which you will use the mod_rewrite module

debug mod_rewrite rules (Apache vhost config)
RewriteLogLevel 8
RewriteLog /var/log/apache2/rewrite.log

redirect all requests to SSL
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]

DirectoryIndex
DirectoryIndex index.php index.php4 index.php3 index.html index.htm index.shtml

apt-get install apache2-utils

ab -n 100 -c 10 http://www.google.com/ > ad.out

deny referrer
RewriteEngine on

# Options +FollowSymlinks

RewriteCond %{HTTP_REFERER} ^http://.*example\.com [NC,OR]
RewriteCond %{HTTP_REFERER} ^http://.*bad-website\.com/ [NC]
RewriteRule ^(.*)$ – [F,L]

test

# echo "SetEnv REGISTER_GLOBALS 0" >> .htaccess
# if this not work disable global php.ini (if you have permisions for this)

#dep# sed -i 's|register_globals = ON|register globals = OFF|g' /etc/php5/apache2/php.ini

# enable mod_rewrite

a2enmod rewrite

service apache2 restart
# change AllowOverride in /etc/apache2/sites-available/default

from: AllowOverride None
to: AllowOverride All

# view php limit

php5 -i | grep memory_limit

ImageMagic

montage - create a composite image by combining several separate images

#!/bin/bash

for i in *a.jpg; do
	F=${i//a.jpg/}	
	echo $F
	montage -label ${F} -compress "Lossless" -geometry +4+4 ${F}a.jpg ${F}b.jpg ./2/${F}.jpg
done

Perl

Execute command
#!/usr/bin/perl

qx"/usr/bin/mysqldump --host=YOUR_HOST_NAME --password=YOUR_DB_PASS --user=YOUR_DB_USER YOUR_DB_NAME | bzip2 --best > export_db.sql.bz2";

linux