Il modo convenzionale usato per cambiare il runlevel usando /etc/inittab è diventato obsoleto con Redhat Enterprise Linux versione 7. Di conseguenza, qualsiasi sistema Linux che utilizza systemd Il demone di gestione del sistema ora si basa su systemctl comando per cambiare il runlevel o per essere più precisi per cambiare la destinazione. Di conseguenza qualsiasi modifica di /etc/inittab il file non avrà effetto su RHEL 7. Il termine runlevel esiste ancora su RHEL 7 e controlliamo il runlevel corrente usando runlevel comando:
[root@rhel7 ~]# runlevel N 3
Tuttavia, per quanto riguarda RHEL 7, invece di runlevel parliamo di obiettivi. Ad esempio, per elencare tutti i target attualmente caricati, possiamo usare il seguente comando linux:
[root@rhel7 ~]# systemctl list-units -t target UNIT LOAD ACTIVE SUB DESCRIPTION basic.target loaded active active Basic System cryptsetup.target loaded active active Encrypted Volumes getty.target loaded active active Login Prompts local-fs-pre.target loaded active active Local File Systems (Pre) local-fs.target loaded active active Local File Systems multi-user.target loaded active active Multi-User System network.target loaded active active Network paths.target loaded active active Paths remote-fs.target loaded active active Remote File Systems slices.target loaded active active Slices sockets.target loaded active active Sockets swap.target loaded active active Swap sysinit.target loaded active active System Initialization timers.target loaded active active Timers LOAD = Reflects whether the unit definition was properly loaded. ACTIVE = The high-level unit activation state, i.e. generalization of SUB. SUB = The low-level unit activation state, values depend on unit type. 14 loaded units listed. Pass --all to see loaded but inactive units, too. To show all installed unit files use 'systemctl list-unit-files'.
Attualmente, il nostro sistema esegue il runlevel 3 che è multi-user.target . Successivamente, possiamo elencare tutti i target di runlevel disponibili utilizzando un comando seguente:
[root@rhel7 ~]# systemctl list-units -t target -a UNIT LOAD ACTIVE SUB DESCRIPTION basic.target loaded active active Basic System cryptsetup.target loaded active active Encrypted Volumes emergency.target loaded inactive dead Emergency Mode final.target loaded inactive dead Final Step getty.target loaded active active Login Prompts graphical.target loaded inactive dead Graphical Interface local-fs-pre.target loaded active active Local File Systems (Pre) local-fs.target loaded active active Local File Systems multi-user.target loaded active active Multi-User System network-online.target loaded inactive dead Network is Online network.target loaded active active Network nss-lookup.target loaded inactive dead Host and Network Name Lookups nss-user-lookup.target loaded inactive dead User and Group Name Lookups paths.target loaded active active Paths remote-fs-pre.target loaded inactive dead Remote File Systems (Pre) remote-fs.target loaded active active Remote File Systems rescue.target loaded inactive dead Rescue Mode shutdown.target loaded inactive dead Shutdown slices.target loaded active active Slices sockets.target loaded active active Sockets swap.target loaded active active Swap sysinit.target loaded active active System Initialization syslog.target not-found inactive dead syslog.target time-sync.target loaded inactive dead System Time Synchronized timers.target loaded active active Timers umount.target loaded inactive dead Unmount All Filesystems LOAD = Reflects whether the unit definition was properly loaded. ACTIVE = The high-level unit activation state, i.e. generalization of SUB. SUB = The low-level unit activation state, values depend on unit type. 26 loaded units listed. To show all installed unit files use 'systemctl list-unit-files'.
L'amministratore di sistema può attivare una qualsiasi delle destinazioni di cui sopra. Ad esempio, attivando graphical.target passeremo effettivamente dal runlevel 3 al runlevel 5 della GUI. Per farlo utilizziamo ancora una volta systemctl comando:
[root@rhel7 ~]# systemctl enable graphical.target --force rm '/etc/systemd/system/default.target' ln -s '/usr/lib/systemd/system/graphical.target' '/etc/systemd/system/default.target'
Come mostrato nell'output sopra, systemctl comando ha cambiato la destinazione predefinita creando un collegamento simbolico in /etc/systemd/system/default.target rendendolo quindi una destinazione di avvio predefinita.