Ninereasons at 20:41, 20 June 2006

2006-06-20T20:41:23Z

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'''rc.subr''' is a subroutine library that was developed primarily for the NetBSD system and imported into FreeBSD where it was further developed. See [http://www.freebsd.org/cgi/man.cgi?query=rc.subr&apropos=0&sektion=0&manpath=FreeBSD+6.0-RELEASE+and+Ports&format=html man rc.subr]

Under FreeBSD 4.x, you may have noticed this file being installed into ''/usr/local/etc/rc.subr'', where it was increasingly used by port-installed daemons. Beginning in FreeBSD 5.0, this file became integral to the FreeBSD startup mechanism for both, base-installed services and port-installed services. At the same time, the directory ''/etc/rc.d'' appeared in FreeBSD, where you will find startup scripts for all base-installed services (so that, for example, ''/etc/rc.sendmail'' disappeared, and was replaced by ''/[[etc/rc.d/sendmail]]'', which uses the ''rc.subr'' mechanism)

Besides being a repository of some very useful and well-written functions, perhaps the chief advantage of using the file is that it ties the configuration, startup and shutdown of these daemons to /[[etc/rc.conf]] in a consistent way. For example, unless the service has an <code>="YES"</code> line in ''rc.conf'', the ''start'' and ''stop'' commands have no effect.

[[User:Jimbo|Some folks]] don't like starting all of their services from ''/etc/rc.conf''. ''' ''rc.subr'' ''' accommodates this preference with the prefixes, ''force'' and ''one''.

Another significant change that this mechanism introduces is, if a startup script ends with ''.sh'', it will be loaded into the current shell (instead of a subshell); ''' ''N.B.'' ''': this means that ''if ''script.sh'' fails'', the remainder of the startup sequence will not be executed.

Finally, a valuable improvement to service startup is better control over the order in which [[daemon]]s are started. See [http://www.freebsd.org/cgi/man.cgi?query=rc&sektion=8&apropos=0&manpath=FreeBSD+6.0-RELEASE+and+Ports man rc(8)] and [http://www.freebsd.org/cgi/man.cgi?query=rcorder&sektion=8&apropos=0&manpath=FreeBSD+6.0-stable man rcorder(8)]

===Examples===
1. Minimal ''rc.d/'' script example, using the new ''rc.subr'' mechanism. Most scripts require little more than this.
#!/bin/sh
#
# PROVIDE: foo
# REQUIRE: bar_service_required_to_precede_foo
# BEFORE: baz_service_requiring_foo_to_precede_it

. /etc/rc.subr

name="foo"
rcvar=`set_rcvar`
command="/usr/local/bin/foo"
load_rc_config $name
run_rc_command "$1"

2. Manually start and stop mysql, even though <code>mysql_enable</code> is set to <code>"NO"</code> (default) in ''rc.conf''.
* Skip all failing pre-requisite "''required_*''" tests (if any).
# /usr/local/etc/rc.d/mysql-server forcestart
# /usr/local/etc/rc.d/mysql-server forcestop
* Skip only the <code>="YES"</code> test
# /usr/local/etc/rc.d/mysql-server onestart
# /usr/local/etc/rc.d/mysql-server onestop

3. List the sequence in which all services will be started, reporting missing dependencies:
# rcorder /etc/rc.d/* /usr/local/etc/rc.d/*

[[Category:Important Config Files]]

Rc.subr - Revision history

Ninereasons at 20:41, 20 June 2006