6.7 Using rc under DragonFly

DragonFly uses the NetBSD® rc.d system for system initialization. Users should notice the files listed in the /etc/rc.d directory. Many of these files are for basic services which can be controlled with the start, stop, and restart options. For instance, sshd(8) can be restarted with the following command:

# /etc/rc.d/sshd restart

This procedure is similar for other services. Of course, services are usually started automatically as specified in rc.conf(5). For example, enabling the Network Address Translation daemon at startup is as simple as adding the following line to /etc/rc.conf:

natd_enable="YES"

If a natd_enable="NO" line is already present, then simply change the NO to YES. The rc scripts will automatically load any other dependent services during the next reboot, as described below.

Since the rc.d system is primarily intended to start/stop services at system startup/shutdown time, the standard start, stop and restart options will only perform their action if the appropriate /etc/rc.conf variables are set. For instance the above sshd restart command will only work if sshd_enable is set to YES in /etc/rc.conf. To start, stop or restart a service regardless of the settings in /etc/rc.conf, the commands should be prefixed with ``force''. For instance to restart sshd regardless of the current /etc/rc.conf setting, execute the following command:

# /etc/rc.d/sshd forcerestart

It is easy to check if a service is enabled in /etc/rc.conf by running the appropriate rc.d script with the option rcvar. Thus, an administrator can check that sshd is in fact enabled in /etc/rc.conf by running:

# /etc/rc.d/sshd rcvar
# sshd
$sshd_enable=YES

To determine if a service is running, a status option is available. For instance to verify that sshd is actually started:

# /etc/rc.d/sshd status
sshd is running as pid 433.

It is also possible to reload a service. This will attempt to send a signal to an individual service, forcing the service to reload its configuration files. In most cases this means sending the service a SIGHUP signal.

The rcNG structure is used both for network services and system initialization. Some services are run only at boot; and the RCNG system is what triggers them.

Many system services depend on other services to function properly. For example, NIS and other RPC-based services may fail to start until after the rpcbind (portmapper) service has started. To resolve this issue, information about dependencies and other meta-data is included in the comments at the top of each startup script. The rcorder(8) program is then used to parse these comments during system initialization to determine the order in which system services should be invoked to satisfy the dependencies. The following words may be included at the top of each startup file:

• PROVIDE: Specifies the services this file provides.

• REQUIRE: Lists services which are required for this service. This file will run after the specified services.

• BEFORE: Lists services which depend on this service. This file will run before the specified services.

• KEYWORD: When rcorder(8) uses the -k option, then only the rc.d files matching this keyword are used. [1] For example, when using -k shutdown, only the rc.d scripts defining the shutdown keyword are used.

  With the -s option, rcorder(8) will skip any rc.d script defining the corresponding keyword to skip. For example, scripts defining the nostart keyword are skipped at boot time.

By using this method, an administrator can easily control system services without the hassle of ``runlevels'' like some other UNIX® operating systems.

Additional information about the DragonFly rc.d system can be found in the rc(8), rc.conf(5), and rc.subr(8) manual pages.