3: [[!toc levels=3]]
5: # The rc.d System
7: NetBSD uses individual scripts for controlling system and service startup,
8: similar to System V, but without runlevels.
9: Nowadays, most Linux distributions switched to systemd, which is a different
10: approach: It does not use scripts anymore, but tries to have everything binary.
11: It also serves for several other purposes, while NetBSD's rc.d system just
12: serves for starting up services at system startup or by user intervention.
14: This chapter is an overview of NetBSD's rc.d system and its configuration.
16: ## Basics
18: The system startup files reside in the `/etc` directory. They are:
20: * `/etc/rc`
21: * `/etc/rc.conf`
22: * `/etc/rc.d/*`
23: * `/etc/rc.lkm`
24: * `/etc/rc.local`
25: * `/etc/rc.shutdown`
26: * `/etc/rc.subr`
27: * `/etc/defaults/*`
28: * `/etc/rc.conf.d/*`
30: First, a look at controlling and supporting scripts (also documented in
33: * After the kernel has initialized all devices at startup, it starts
35: which in turn runs `/etc/rc`.
37: * `/etc/rc` sorts the scripts in `/etc/rc.d` using
39: and then runs them in that order. See below and the manpage for details of
40: how the order of rc.d scripts is determined.
42: * `/etc/rc.subr` contains common functions used by `/etc/rc` and various rc.d
45: * When shutting down the system with
47: `/etc/rc.shutdown` is run, which runs the scripts in `/etc/rc.d` in
48: reverse order (as defined by
51: *Note*: If you shut down the system using the
53: command, these scripts will not be run.
55: There are some special scripts outside the `rc.d` directory, which are also
58: * `/etc/rc.lkm` loads or unloads Loadable Kernel Modules (LKMs). See
60: and `/etc/rc.d/lkm`.
62: * `/etc/rc.local` is almost the last script called at boot up. This script can
63: be edited by the administrator to start local daemons that don't fit the
64: rc.d model, or do maintenance that should be done only once at startup.
66: rc.d scripts are controlled by a central configuration file, `/etc/rc.conf`,
67: which loads its default settings from `/etc/defaults/rc.conf`. If you want to
68: change a default setting, do not edit `/etc/defaults/rc.conf`; instead, override
69: the setting in `/etc/rc.conf`.
71: It is a good idea to read the
73: man page to learn about the services that are by default available to you.
75: The following example shows how to enable the SSH daemon, which is disabled by
78: # cd /etc; grep ssh defaults/rc.conf
79: sshd=NO sshd_flags=""
80: # echo "sshd=YES" >> rc.conf
82: Now [sshd(8)](http://netbsd.gw.com/cgi-bin/man-cgi?sshd+8+NetBSD-5.0.1+i386)
83: will be started automatically at system startup. The next section describes how
84: to start and stop services at any time.
86: Last but not least, files can be created in the `/etc/rc.conf.d/` directory to
87: override the behavior of a given rc.d script without editing the script itself.
89: ## The rc.d scripts
91: The actual scripts that control services are in `/etc/rc.d`. These scripts are
92: automatically run at boot time, but they can be called manually if necessary.
93: The following example shows how to start the SSH daemon that we enabled in the
94: previous section:
96: # /etc/rc.d/sshd start
97: Starting sshd.
99: Later, if you wish to stop the SSH daemon, run the following command:
101: # /etc/rc.d/sshd stop
102: Stopping sshd.
103: Waiting for PIDS: 123.
105: The rc.d scripts take one of the following arguments:
107: * `start`
108: * `stop`
109: * `restart`
110: * `status`
112: Some scripts may support other arguments (e.g., `reload`), but every script will
113: support at least the above commands.
115: As an example, after adding a new record to a
117: database, the daemon can be told to reload its configuration files with the
118: following command:
120: # /etc/rc.d/named reload
121: Reloading named config files.
123: Note that all of the commands discussed above will only take action if the
124: particular service is enabled in `/etc/rc.conf`. It is possible to bypass this
125: requirement by prepending `one` to the command, as in:
127: # /etc/rc.d/httpd start
128: $httpd is not enabled - see rc.conf(5).
129: Use the following if you wish to perform the operation:
130: /etc/rc.d/httpd onestart
131: # /etc/rc.d/httpd onestart
132: Starting httpd.
134: The above command will allow you to start the
136: service one time. To stop a service that has been started in this manner, pass
137: `onestop` to the script.
139: ## Order/dependencies of start determined by rcorder
141: The startup system of every Unix system determines, in one way or another, the
142: order in which services are started. On some Unix systems this is done by
143: numbering the files and/or putting them in separate run level directories.
144: Solaris relies on wildcards like `/etc/rc.d/S*` being sorted numerically
145: when expanded. Some simply put all the commands that should be started into a
146: single monolithic script (this is the traditional BSD method, and is what NetBSD
147: did before the rc.d system). On modern NetBSD this is done by the rc.d scripts
148: and their contents. Please note that NetBSD does not have multiple runlevels as
149: found in SysV-style systems like Solaris and Linux.
151: At the beginning of each rc.d script there is a series of commented out lines
152: that have one of the following items in them:
154: * `REQUIRE`
155: * `PROVIDE`
156: * `BEFORE`
157: * `KEYWORD`
159: These describe the dependencies of that particular script and allow rcorder to
160: easily work either `up` or `down` as the situation requires. As an example, here
161: is the ordering information contained in `/etc/rc.d/nfsd`:
164: # PROVIDE: nfsd
165: # REQUIRE: rpcbind mountd
168: Here we can see that this script provides the `nfsd` service and that it
169: requires `rpcbind` and `mountd` to be running first. The
171: utility is used at system startup time to read through all the rc.d scripts and
172: determine the order in which they should be run.
174: ## rc.d scripts of additional services
176: Packages you install additionally won't be listed in the rc.conf(5) manpage.
177: Packages installing services which can be started with an rc.d script tell you
178: so after they are installed, along with the variable that is used for starting
179: them (usually, it has the same name as the service itself).
181: Then, you usually have to copy them from `/usr/pkg/share/examples/rc.d` to
182: `/etc/rc.d` for `rc` to automatically find them, or add the line
184: rc_directories="/etc/rc.d /usr/pkg/share/examples/rc.d"
186: to your `/etc/rc.conf`.
188: If you forgot the name of the service variable, you can have a look at the rc.d
189: script itself. The variable `rcvar` (usually set to `$name`) will tell you.
190: E.g., to find the name of variable to start fscd, run
192: $ grep ^rcvar /etc/rc.d/fscd
194: $ grep ^name /etc/rc.d/fscd # Aaaw, no direct rcvar.
197: Thus, you need in your `/etc/rc.conf` the entry:
201: ## Additional Reading
203: Luke Mewburn, one of the principal designers of the rc.d system, gave a
204: presentation on the system at USENIX 2001. It is available in
205: [PDF](http://www.mewburn.net/luke/papers/rc.d.pdf) format.
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