Systemd has replaced sysVinit as the default service manager in RHEL 7. Some of the sysVinit commands have been symlinked to their RHEL 7 counterparts, however this will eventually be deprecated in favor of the standard systemd commands in the future.
SysVinit V/s systemd runlevels
Here is a comparison between SysVinit runlevels V/s systemd targets.
|Sysvinit Runlevel||Systemd Target||Function|
|0||runlevel0.target, poweroff.target||System halt/shutdown|
|1, s, single||runlevel1.target, rescue.target||Single-user mode|
|2, 4||runlevel2.target, runlevel4.target, multi-user.target||User-defined/Site-specific runlevels. By default, identical to 3.|
|3||runlevel3.target, multi-user.target||Multi-user, non-graphical mode, text console only|
|5||runlevel5.target, graphical.target||Multi-user, graphical mode|
Changing runlevels with systemd
The runlevel target can be changed by using the systemctl isolate command :
# systemctl isolate multi-user.target
To view what targets are available you can issue the list-units option with the type target
# systemctl list-units --type=target
Run level 3 is emulated by multi-user.target. This is done by symbolic link and can be used interchangeably
# systemctl isolate multi-user.target # systemctl isolate runlevel3.target # ls -l /usr/lib/systemd/system/runlevel3.target lrwxrwxrwx 1 root root 17 Oct 18 11:41 /usr/lib/systemd/system/runlevel3.target -> multi-user.target
Run level 5 is emulated by graphical.target. This is also done by symbolic link and can be used interchangeably
# systemctl isolate graphical.target # systemctl isolate runlevel5.target # ls -l /usr/lib/systemd/system/runlevel5.target lrwxrwxrwx 1 root root 16 Oct 18 11:41 /usr/lib/systemd/system/runlevel5.target -> graphical.target
Changing the default runlevel
The default runlevel can be changed by using the set-default option.
# systemctl set-default multi-user.target
To get the currently set default, you can use the get-default option.
# systemctl get-default
The default runlevel in systemd can also be set using the below method (not recommended though).
# ln -sf /lib/systemd/system/
The default target can also be set in the kernel line during boot by adding the following option :