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WebServers > Apache

Apache Web Server

Installing Apache under Debian

Installing apache2 is as easy as running:

#apt-get install apache2

MPM selection in Debian Jessie

With Apache 2.4 in Debian Jessie the Multi-Processing Module used is no longer selected by installing one of the apache2-mpm- packages. MPM modules are enabled and disabled using the a2enmod and a2dismod commands just like with any other module. Only one MPM may be used at a time.

The default MPM used by Apache 2.4 in Jessie is mpm_event. An example of switching to mpm_worker:

# a2dismod mpm_event
# a2enmod mpm_worker

Some modules such as libapache2-mod-php5 that require using mpm_prefork will switch to this MPM as part of the package's post installation script.

MPM selection in Debian Wheezy and earlier

APT will automatically select one of the four engines, usually apache2-mpm-prefork or apache2-mpm-worker (apache2-mpm-event and apache2-mpm-itk aren't recommended). The package's description contains an overview of their differences.

Script / Dynamic content

Apache can use any external program and scripting language, through CGI or FastCgi (libapache2-mod-fcgid).

Apache can also embed some scripts interpreters or connect to an application server to generate dynamic content:


Debian has many modules for Apache, which package names are usually prefixed with libapache2-mod

Once installed, modules can be enabled or disabled with the commands a2enmod and a2dismod.

It seems that there are exceptions as with the module mod_evasive, this module is activated automatically. More information about the module mod_evasive, in French : Apache mod_evasive en français.

Multiple Instances

The scripts apache2ctl, a2enmod, a2ensite, ... and the init script have some support for handling multiple instances of apache2 running on the same machine.

The basic idea is to copy /etc/apache2 to /etc/apache2-xxx. An example script that demonstrates what else needs to be done can be found in /usr/share/doc/apache2/examples/setup-instance. Use with:

sh /usr/share/doc/apache2/examples/setup-instance xxx

You can then use a2enmod-xxx, /etc/init.d/apache2-xxx, ... as usual, and they will affect the new instance of apache2.

see /usr/share/doc/apache2/README.multiple-insances for full details

Other stuff

#apt-cache search apache | less


Apache user (www-data)
Debian's Apache packages come configured to run as user 'www-data'. This is potentially confusing: files to be served by apache should not be owned by 'www-data', as apache should not normally be allowed to modify them (i.e. as long as you're not running a wiki).
Apache v1.3 is officially encouraging users to switch to apache v2.2. DebianLenny and later releases, don't ship Apache v1.x.
(apache 1.3 release notes: "We strongly recommend that users of all earlier versions, including 1.3 family release, upgrade to to the current 2.2 version as soon as possible.")

See /usr/share/doc/apache2.2-common/NEWS.Debian.gz


Packaging modules


See Also