apache2 is the Apache HyperText Transfer Protocol (HTTP) server program. It is designed to be run as a standalone daemon process. When used like this it will create a pool of child processes or threads to handle requests.
In general, apache2 should not be invoked directly, but rather should be
invoked via /etc/init.d/apache2 or apache2ctl. The default Debian
configuration requires environment variables that are defined in
/etc/apache2/envvars and are not available if apache2 is started directly.
However, apache2ctl can be used to pass arbitrary arguments to apache2.
The full documentation is available in the apache2-doc package or at
http://httpd.apache.org/docs/2.2/ . Information about Debian specific changes
and configuration can be found in
Set the initial value for the ServerRoot directive to serverroot. This can be overridden by the ServerRoot directive in the configuration file.
Uses the directives in the file config on startup. If config does not begin with a /, then it is taken to be a path relative to the ServerRoot. The default is /etc/apache2/apache2.conf.
Signals apache2 to start, restart, or stop. See Stopping Apache for more information.
Process the configuration directive before reading config files.
Process the configuration directive after reading config files.
Sets a configuration parameter which can be used with <IfDefine> sections in the configuration files to conditionally skip or process commands at server startup and restart.
Sets the LogLevel to level during server startup. This is useful for temporarily increasing the verbosity of the error messages to find problems during startup.
Send error messages during server startup to file.
When the server is compiled using the SHARED_CORE rule, this specifies the directory for the shared object files.
Output a short summary of available command line options.
Output a list of modules compiled into the server. This will not list dynamically loaded modules included using the LoadModule directive.
Output a list of directives together with expected arguments and places where the directive is valid.
Dump a list of loaded Static and Shared Modules.
Show the settings as parsed from the config file (currently only shows the virtualhost settings).
Run syntax tests for configuration files only. The program immediately exits after these syntax parsing tests with either a return code of 0 (Syntax OK) or return code not equal to 0 (Syntax Error). If -D DUMP_VHOSTS is also set, details of the virtual host configuration will be printed. If -D DUMP_MODULES is set, all loaded modules will be printed.
Print the version of apache2, and then exit.
Print the version and build parameters of apache2, and then exit.
Run apache2 in debug mode. Only one worker will be started and the server will not detach from the console.