When linux based system start booting. Kernel select one of available target and load services accordingly.
A target is a mode in Centos 7 and Red hat enterprise . systemd is responsible to select the target. A systemd target is same a runlevels in centos6.
systemd target is replacement of “System V init” system. systemd is a system daemon
systemd is designed for better handling of dependencies and has ability to handle more work in parallel at system startup
There are 7 target or levels available in Centos7
| Run-level | Target | Explanation |
| 0 | poweroff.target | This run level/target is used by systemd to power-off or halt the system |
| 1 | rescue.target | This run level/target is used by systemd to boot the system in rescue or recovery mode. It is very helpful if some goes wrong you can change the configuration in that mode |
| 2 | multi-user.target | This run level/target is used by systemd to boot system into multi-user environment so user can work in parallel |
| 3 | multi-user.target | |
| 4 | multi-user.target | |
| 5 | graphical.target | This run level/target is used by systemd to boot system into multi-user graphical environment so user can work in parallel in graphical mode |
| 6 | reboot.target | This run level/target is used by systemd to reboot the system |
How to get list to available Targets
[kmehmood@svn-dev ~]$ systemctl list-units --type=target
Note: Above statement will only share list of active available target
Output of above statement
How to get list of available target including inactive
[kmehmood@svn-dev ~]$ systemctl list-units --type=target --all
Note: Above statement will only share list of all available targets
There are two type of default targets
1: multi-user.target
2: graphical.target
How to find default target
[kmehmood@svn-dev ~]$ systemctl get-default graphical.target
Output of above statement
How to change default mode
Syntax: systemctl set-default target_name
[root@svn-dev ~]# systemctl set-default multi-user.target
Confirm the default runlevel.
[root@svn-dev ~]# systemctl get-default multi-user.target
Reboot and check it out.
[root@svn-dev ~]# reboot
we can also check target levels available
[kmehmood@svn-dev ~]$ ls /lib/systemd/system/runlevel*target -l lrwxrwxrwx. 1 root root 15 Jan 23 19:10 /lib/systemd/system/runlevel0.target -> poweroff.target lrwxrwxrwx. 1 root root 13 Jan 23 19:10 /lib/systemd/system/runlevel1.target -> rescue.target lrwxrwxrwx. 1 root root 17 Jan 23 19:10 /lib/systemd/system/runlevel2.target -> multi-user.target lrwxrwxrwx. 1 root root 17 Jan 23 19:10 /lib/systemd/system/runlevel3.target -> multi-user.target lrwxrwxrwx. 1 root root 17 Jan 23 19:10 /lib/systemd/system/runlevel4.target -> multi-user.target lrwxrwxrwx. 1 root root 16 Jan 23 19:10 /lib/systemd/system/runlevel5.target -> graphical.target lrwxrwxrwx. 1 root root 13 Jan 23 19:10 /lib/systemd/system/runlevel6.target -> reboot.target
output
