Process Management

Daemontools

flag	action
-u	Up. If the service is not running, start it. If the service stops, restart it.
-d	Down. If the service is running, send it a TERM signal and then a CONT signal. After it stops, do not restart it.
-o	Once. If the service is not running, start it. Do not restart it if it stops.
-p	Pause. Send the service a STOP signal.
-c	Continue. Send the service a CONT signal.
-h	Hangup. Send the service a HUP signal.
-a	Alarm. Send the service an ALRM signal.
-i	Interrupt. Send the service an INT signal.
-t	Terminate. Send the service a TERM signal.
-k	Kill. Send the service a KILL signal.

upstart

Included in CentOS 6, Ubuntu

http://upstart.ubuntu.com/

Scripts in /etc/init

Disable services by using .override instead of .conf on the files in /etc/init

echo manual > /etc/init/apache2.override

init

Traditional init systems used /etc/inittab

Runlevels

# See the current runlevel
runlevel
who -r

# Change runlevel
init 5
telinit 5

/etc/rc.d

File links that start with S start the service, K stops the service. Numbers determine order of operation.

chkconfig

Generally only available on RHEL-ish

# List services
chkconfig --list

# Turn httpd on at levels 2 and 4
chkconfig --level 24 httpd on

LSB

level	desc
0	halt
1	single user mode
2	multi user mode
3	multi user mode w/ networking
4	not used/user-definable
5	runlevel 3 plus graphics
6	reboot