init/systemd
innserv -d
after editing the default-stop/start parameters, recreate the appropriate start and kill scripts in the rcx.d directory
emergency.target
emergency shell
/etc/inittab
file that defines runlevels
poweroff.target
halts the system, symbolic link to runlevel0.target
reload
init parameter rereads the associated service's configuration file
start
init parameter starts the associated service
stop
init parameter stops the associated service
restart
init parameter stops then starts the associated service
status
init parameter views the status of the service
/etc/init.d
location of bsd style init scripts
/etc/rc.d
location of system v init scripts
systemctl
manage services/runlevels in systemd
systemctl set-default
modifies the default boot target
multi-user.target
multi-user, non graphical mode. symbolic link to runlevel3.target
graphical.target
multiuser graphical mode, symbolic link to runlevel5.target
0
runlevel halts the system
6
runlevel reboots the system
5
runlevel starts linux in graphical multiuser mode with networking enabled
2
runlevel starts linux in multiuser mode with networking disabled
3
runlevel starts linux in multiuser mode with networking enabled
1
runlevel starts linux in single user mode
rc.local
similar to the bsd style init boot.local. can add commands to be run at startup.
rescue.target
single user mode, symbolic link to runlevel1.target
chkconfig -s
specify the runlevels you want a daemon to start in
systemctl start
start a service in systemd
systemctl enable
start a service on boot
systemctl stop
stop a service in systemd
chkconfig -l
view current runlevel configuration for a service, or all daemons
systemctl get-default
view the current default runlevel
rc
bsd and sysv script used to switch between runlevels while the system is running
boot.local
bsd script run by init at startup. can be modified to run commands automatically at startup
boot
bsd script run by init when the system first starts. loads kernel modules, verifies file system, sets the system clock
halt
bsd script used to stop or reboot system. run when runlevel is changed to 0 or 6
systemctl isolate
change runlevels with systemctl
systemctl status
check the status of a service in systemd
systemctl is-enabled
check to see if a service is enabled/disabled on boot
chkconfig
configure a daemon to start at it's default runlevels
4
custom runlevel
insserv -r
disable a service (remove all links from rcx.d) and stop the service if currently running
systemctl disable
disable a service on boot
/etc/systemd/system/default.target
pointer to default boot target. replaces /etc/inittab
insserv
reads info in INIT INFO block of an init script to determine which runlevels the associated service should run in by default
reboot.target
reboot, symbolic link to runlevel6.target
init q
reread the /etc/inittab file
systemctl restart
restart a service in systemd
rc.sysinit
sysv script similar to the boot script on systems with bsd style init. sets the path, checks file systems for errors...
