MESSAGE
| DATE | 2015-11-04 |
| FROM | ruben safir
|
| SUBJECT | Subject: [Hangout-NYLXS] openrc tips
|
http://www.libregeek.org/2014/02/11/creating-startup-init-script-openrc/
Creating a Startup init Script For OpenRC
Even though OpenRC init scripts use the “init.d” type implementation, I
still wanted to break this how to into a separate article. The guide
will detail the bare basics of init implementation with OpenRC.
Specification and Comparison
The OpenRC system does not support script-specific restart
functionality. Instead, the script needs to check the contents of the
RC_CMD variable to see if a function (be it start() or stop()) is called
as part of a restart or not.
It is very important to start your script with the proper environment.
The OpenRC script needs to start with “#!/sbin/runscript”, as seen below
Overview of Run Levels
OpenRC uses run levels just like sysV, and in similar practice to how
systemd uses single user and multi user “targets.” Below is a table and
explanation of each level (click image to enlarge):
Screenshot from 2014-02-11 13:10:48
Creating your OpenRC init script
OpenRC uses simple scripts to enable an uncomplicated method of
implementation. Below is a code template that outlines a basic OpenRC
init script. FOO is a common “general” place holder for whichever
program you are trying to implement.
[code language=”bash” collapse=”true”]#!/sbin/runscript
#
# Start ddclient that provides support for updating dynamic DNS services.
#
depend() {
need net
use dns logger
}
start() {
DDCLIENT="/usr/sbin/ddclient"
CONF="/etc/ddclient/ddclient.conf"
PIDFILE="/var/run/ddclient.pid"
test -x $DDCLIENT || exit 0
test -f $CONF || exit 0
ebegin "Starting ddclient…"
start-stop-daemon –start –quiet –pidfile $PIDFILE –exec $DDCLIENT –chdir
/etc/ddclient — -file $CONF
eend $?
}
stop() {
ebegin "Stopping ddclient…"
start-stop-daemon –stop –quiet –pidfile $PIDFILE –retry SIGTERM/10
eend $?
}
[/code]
Implementing the script
What I do like about OpenRC’s init scripts, is how easy it is to
implement them. All of the OpenRC init scripts are stored in either the
“/etc/rc.d/init.d/” directory, or the “/etc/init.d” directory. These
scripts are used to control system startup and shutdown, in contrast to
“startup applications” that are in user space, and not part of the
system startup at boot time.
An example of this is the CUPS system daemon:
/etc/init.d/httpd start
1
/etc/init.d/httpd start
The first line will start the service, but will not persist on boot up
until you update your init scripts (see below).
Update your init scripts
When you are finished implementing the script into the system, be sure
to update the init scripts that load on boot up:
update-rc.d
1
update-rc.d
Summary
That should be all that is needed to get you on the road to making your
own init scripts for OpenRC init systems.
Enjoy,
-mikeyd
Sources:
http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=2&chap=4&style=printable
http://wiki.alpinelinux.org/wiki/Writing_Init_Scripts
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