Diff for /wikisrc/guide/rc.mdwn between versions 1.6 and 1.7

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 **Contents**  This page was moved to:
   [The NetBSD Guide - The rc.d System](//www.NetBSD.org/docs/guide/en/chap-rc.html)
 [[!toc levels=3]]  
   
 # The rc.d System  
   
 NetBSD uses individual scripts for controlling system and service startup,  
 similar to System V, but without runlevels.  
 Nowadays, most Linux distributions switched to systemd, which is a different  
 approach: It does not use scripts anymore, but tries to have everything binary.  
 It also serves for several other purposes, while NetBSD's rc.d system just  
 serves for starting up services at system startup or by user intervention.  
   
 This chapter is an overview of NetBSD's rc.d system and its configuration.  
   
 ## Basics  
   
 The system startup files reside in the `/etc` directory. They are:  
   
  * `/etc/rc`  
  * `/etc/rc.conf`  
  * `/etc/rc.d/*`  
  * `/etc/rc.local`  
  * `/etc/rc.shutdown`  
  * `/etc/rc.subr`  
  * `/etc/defaults/*`  
  * `/etc/rc.conf.d/*`  
   
 First, a look at controlling and supporting scripts (also documented in  
 [[!template id=man name="rc" section="8"]]):  
   
  * After the kernel has initialized all devices at startup, it starts  
    [[!template id=man name="init" section="8"]],  
    which in turn runs `/etc/rc`.  
   
  * `/etc/rc` sorts the scripts in `/etc/rc.d` using  
    [[!template id=man name="rcorder" section="8"]]  
    and then runs them in that order. See below and the manpage for details of  
    how the order of rc.d scripts is determined.  
   
  * `/etc/rc.subr` contains common functions used by `/etc/rc` and various rc.d  
    scripts.  
   
  * When shutting down the system with  
    [[!template id=man name="shutdown" section="8"]],  
    `/etc/rc.shutdown` is run, which runs the scripts in `/etc/rc.d` in  
    reverse order (as defined by  
    [[!template id=man name="rcorder" section="8"]]).  
   
    *Note*: If you shut down the system using the  
    [[!template id=man name="halt" section="8"]]  
    command, these scripts will not be run.  
   
 There are some special scripts outside the `rc.d` directory, which are also  
 run:  
   
  * `/etc/rc.local` is almost the last script called at boot up. This script can  
    be edited by the administrator to start local daemons that don't fit the  
    rc.d model, or do maintenance that should be done only once at startup.  
   
 rc.d scripts are controlled by a central configuration file, `/etc/rc.conf`,  
 which loads its default settings from `/etc/defaults/rc.conf`. If you want to  
 change a default setting, do not edit `/etc/defaults/rc.conf`; instead, override  
 the setting in `/etc/rc.conf`.  
   
 It is a good idea to read the  
 [[!template id=man name="rc.conf" section="5"]]  
 man page to learn about the services that are by default available to you.  
   
 The following example shows how to enable the SSH daemon, which is disabled by  
 default:  
   
     # cd /etc; grep ssh defaults/rc.conf  
     sshd=NO                 sshd_flags=""  
     # echo "sshd=YES" >> rc.conf  
   
 Now [[!template id=man name="sshd" section="8"]]  
 will be started automatically at system startup. The next section describes how  
 to start and stop services at any time.  
   
 Last but not least, files can be created in the `/etc/rc.conf.d/` directory to  
 override the behavior of a given rc.d script without editing the script itself.  
   
 ## The rc.d scripts  
   
 The actual scripts that control services are in `/etc/rc.d`. These scripts are  
 automatically run at boot time, but they can be called manually if necessary.  
 The following example shows how to start the SSH daemon that we enabled in the  
 previous section:  
   
     # /etc/rc.d/sshd start  
     Starting sshd.  
   
 Later, if you wish to stop the SSH daemon, run the following command:  
   
     # /etc/rc.d/sshd stop  
     Stopping sshd.  
     Waiting for PIDS: 123.  
   
 The rc.d scripts take one of the following arguments:  
   
  * `start`  
  * `stop`  
  * `restart`  
  * `status`  
   
 Some scripts may support other arguments (e.g., `reload`), but every script will  
 support at least the above commands.  
   
 As an example, after adding a new record to a  
 [[!template id=man name="named" section="8"]]  
 database, the daemon can be told to reload its configuration files with the  
 following command:  
   
     # /etc/rc.d/named reload  
     Reloading named config files.  
   
 Note that all of the commands discussed above will only take action if the  
 particular service is enabled in `/etc/rc.conf`. It is possible to bypass this  
 requirement by prepending `one` to the command, as in:  
   
     # /etc/rc.d/httpd start  
     $httpd is not enabled - see rc.conf(5).  
     Use the following if you wish to perform the operation:  
       /etc/rc.d/httpd onestart  
     # /etc/rc.d/httpd onestart  
     Starting httpd.  
   
 The above command will allow you to start the  
 [[!template id=man name="httpd" section="8"]]  
 service one time. To stop a service that has been started in this manner, pass  
 `onestop` to the script.  
   
 ## Order/dependencies of start determined by rcorder  
   
 The startup system of every Unix system determines, in one way or another, the  
 order in which services are started. On some Unix systems this is done by  
 numbering the files and/or putting them in separate run level directories.  
 Solaris relies on wildcards like `/etc/rc[23].d/S*` being sorted numerically  
 when expanded. Some simply put all the commands that should be started into a  
 single monolithic script (this is the traditional BSD method, and is what NetBSD  
 did before the rc.d system). On modern NetBSD this is done by the rc.d scripts  
 and their contents. Please note that NetBSD does not have multiple runlevels as  
 found in SysV-style systems like Solaris and Linux.  
   
 At the beginning of each rc.d script there is a series of commented out lines  
 that have one of the following items in them:  
   
  * `REQUIRE`  
  * `PROVIDE`  
  * `BEFORE`  
  * `KEYWORD`  
   
 These describe the dependencies of that particular script and allow rcorder to  
 easily work either `up` or `down` as the situation requires. As an example, here  
 is the ordering information contained in `/etc/rc.d/nfsd`:  
   
     ...  
     # PROVIDE: nfsd  
     # REQUIRE: rpcbind mountd  
     ...  
   
 Here we can see that this script provides the `nfsd` service and that it  
 requires `rpcbind` and `mountd` to be running first. The  
 [[!template id=man name="rcorder" section="8"]]  
 utility is used at system startup time to read through all the rc.d scripts and  
 determine the order in which they should be run.  
   
 ## rc.d scripts of additional services  
   
 Packages you install additionally won't be listed in the rc.conf(5) manpage.  
 Packages installing services which can be started with an rc.d script tell you  
 so after they are installed, along with the variable that is used for starting  
 them (usually, it has the same name as the service itself).  
   
 Then, you usually have to copy them from `/usr/pkg/share/examples/rc.d` to  
 `/etc/rc.d` for `rc` to automatically find them, or add the line  
   
     rc_directories="/etc/rc.d /usr/pkg/share/examples/rc.d"  
   
 to your `/etc/rc.conf`.  
   
 If you forgot the name of the service variable, you can have a look at the rc.d  
 script itself. The variable `rcvar` (usually set to `$name`) will tell you.  
 E.g., to find the name of variable to start fscd, run  
   
     $ grep ^rcvar /etc/rc.d/fscd  
         rcvar=${name}  
         $ grep ^name /etc/rc.d/fscd   # Aaaw, no direct rcvar.  
         name="fscd"  
   
 Thus, you need in your `/etc/rc.conf` the entry:  
   
     fscd="YES"  
   
 ## Additional Reading  
   
 Luke Mewburn, one of the principal designers of the rc.d system, gave a  
 presentation on the system at USENIX 2001. It is available in  
 [PDF](http://www.mewburn.net/luke/papers/rc.d.pdf) format.  
   

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