# Starting Apache

## Invoking Apache

The `httpd` program is usually run as a daemon which executes continuously, handling requests. It is possible to invoke Apache by the Internet daemon `inetd` each time a connection to the HTTP service is made (use the ServerType directive) but this is not recommended.

## Command line options

The following options are recognized on the httpd command line:

`-d` serverroot
  Set the initial value for the ServerRoot variable to serverroot. This can be overridden by the ServerRoot command in the configuration file. The default is `/usr/local/etc/httpd`.
`-f` config
  Execute the commands 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 `conf/httpd.conf`.
`-X`
  Run in single-process mode, for internal debugging purposes only; the daemon does not detach from the terminal or fork any children. Do NOT use this mode to provide ordinary web service.
`-v`
  Print the version of httpd, and then exit.
`-h`
  Give a list of directives together with expected arguments and places where the directive is valid. (New in Apache 1.2)
`-l`
  Give a list of all modules compiled into the server.
`-?`
  Print a list of the httpd options, and then exit.

## Configuration files

The server will read three files for configuration directives. Any directive may appear in any of these files. The the names of these files are taken to be relative to the server root; this is set by the ServerRoot directive, or the `-d` command line flag. Conventionally, the files are:

`conf/httpd.conf`
  Contains directives that control the operation of the server daemon. The filename may be overridden with the `-f` command line flag.
`conf/srm.conf`
  Contains directives that control the specification of documents that the server can provide to clients. The filename may be overridden with the ResourceConfig directive.
`conf/access.conf`
  Contains directives that control access to documents. The filename may be overridden with the AccessConfig directive.

However, these conventions need not be adhered to.

The server also reads a file containing mime document types; the filename is set by the TypesConfig directive, and is `conf/mime.types` by default.

## Log files

### security warning

Anyone who can write to the directory where Apache is writing a log file can almost certainly gain access to the uid that the server is started as, which is normally root. Do NOT give people write access to the directory the logs are stored in without being aware of the consequences; see the security tips document for details.

### pid file

On daemon startup, it saves the process id of the parent httpd process to the file `logs/httpd.pid`. This filename can be changed with the PidFile directive. The process-id is for use by the administrator in restarting and terminating the daemon; A HUP or USR1 signal causes the daemon to re-read its configuration files and a TERM signal causes it to die gracefully. For more information see the Stopping and Restarting page.

If the process dies (or is killed) abnormally, then it will be necessary to kill the children httpd processes.

### Error log

The server will log error messages to a log file, `logs/error_log` by default. The filename can be set using the ErrorLog directive; different error logs can be set for different virtual hosts.

### Transfer log

The server will typically log each request to a transfer file, `logs/access_log` by default. The filename can be set using a TransferLog directive; different transfer logs can be set for different virtual hosts.