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MaoPU
Asked: 2010-09-16 20:46:16 +0800 CST

apache2: Get a list of registered handlers

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Is it possible, to get a list of all handlers from apache? With setHandler it is possible to create handlers.

One possible usage would be to add a handler for a specific file extension (addHandler). Knowing all the possible handlers and their identifier would ease the process of matching them to a file extension (or in case of URL handlers creating a list of possible URLs).

The handlers must be managed in apache core in some kind of list - how is it possible to get this list out?

apache-2.2 handler-mappings

2 Answers

  1. Apache does not expose a list of configured handlers. Not using apachectl, not with anything else.

    The best method that I could find to get a list of configured handlers is to simply grep the Apache configuration folder for Handler to catch all AddHandler and SetHandler declarations.

    For Debian-based (Ubuntu) hosts

    $ grep -ir "Handler" /etc/apache2/*
mods-enabled/php5.conf: SetHandler application/x-httpd-php
mods-enabled/php5.conf: SetHandler application/x-httpd-php-source
apache2.conf:           SetHandler server-status
mods-available/info.conf:    SetHandler server-info
mods-available/ldap.conf:    SetHandler ldap-status
mods-available/status.conf:  SetHandler server-status
mods-available/php5.conf:    SetHandler application/x-httpd-php
mods-available/php5.conf:    SetHandler application/x-httpd-php-source
sites-available/default:     AddHandler cgi-script .cgi
sites-enabled/000-default:   AddHandler cgi-script .cgi

    For Redhat-based (Fedora, CentOS) hosts

    $ grep -ir "Handler" /etc/httpd/*
conf.d/php.conf:  AddHandler php5-script .php
conf/httpd.conf:  #AddHandler cgi-script .cgi
conf/httpd.conf:  #AddHandler send-as-is asis
conf/httpd.conf:  AddHandler type-map var
conf/httpd.conf:  #ErrorDocument 404 "/cgi-bin/missing_handler.pl"
conf/httpd.conf:     AddHandler type-map var
conf/httpd.conf:#    SetHandler server-status
conf/httpd.conf:#    SetHandler server-info
conf.d/fcgid.conf:   AddHandler fcgid-script fcg fcgi fpl
conf.d/perl.conf:#   SetHandler perl-script
conf.d/perl.conf:#   SetHandler perl-script

    Note that not all handlers found are in fact registered! Search in mods-enabled (Debian) and disregard lines starting with # to narrow down only the registered handlers.

    As suggested by Jenny in the comments, commented lines can be removed by filtering the output with grep -Pv '^[^ ]*:\s*#'. Here is the final command for Debian-based machines:

    $ grep -ir "Handler" /etc/apache2/* | grep -Pv '^[^ ]*:\s*#'

    And for Redhat-based machines:

    $ grep -ir "Handler" /etc/httpd/* | grep -Pv '^[^ ]*:\s*#'

    In the comments user gogoud provides an additional way to strip out commented handlers, thus returning only registered handlers:

    // Debian or Ubuntu
$ grep -R "Handler" /etc/apache2/*enabled* | sed 's/#.*//;/^[^:]*:\s*$/d'

// Redhat, CentoOS, Fedora
$ grep -R "Handler" /etc/httpd/*enabled* | sed 's/#.*//;/^[^:]*:\s*$/d'
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  2. This is isn't quite what you want, but if you enable the server-info handler in your config, the output will tell you which modules have handlers and which don't, like this:

    Module Name: mod_negotiation.c
Content handlers: yes
....
Module Name: mod_mime.c
Content handlers: none
....

    This was with Apache 2.2, so perhaps later versions will give you more useful output.

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