Redhat7:systemd targets - Revision history

Michael: /* Enter Emergency Mode */

2015-01-07T09:29:38Z

Enter Emergency Mode

Michael: /* Change the default target */

2015-01-07T09:27:23Z

Change the default target

Michael: /* Previously and Now.. */

2015-01-07T09:23:18Z

Previously and Now..

Michael: /* Previously and Now... */

2015-01-07T09:18:52Z

Previously and Now...

Michael: Created page with "== Previously and Now... =="

2015-01-07T09:02:50Z

Created page with "== Previously and Now... =="

New page

== Previously and Now... ==

@@ Line 96: / Line 96: @@
 systemctl --no-wall emergency
 systemctl isolate emergency.target
-<bash/>
+</syntaxhighlight>

← Older revision		Revision as of 09:27, 7 January 2015
Line 78:		Line 78:
	systemctl set-default name.target		systemctl set-default name.target
	</syntaxhighlight>		</syntaxhighlight>
		+
		+
		+	== Enter Rescue Mode ==
		+
		+	<syntaxhighlight>
		+	systemctl rescue
		+	systemctl --no-wall rescue
		+	systemctl isolate rescue.target
		+	</syntaxhighlight>
		+
		+	== Enter Emergency Mode ==
		+
		+	In the event the resuce mode fails or does not allow the problem to be fixed emergency mode is a last resort. Booting the system is the most minimal environment possible. Mounting the root file system in read only mode, and starting the bare essential services
		+
		+	<syntaxhighlight>
		+	systemctl emergency
		+	systemctl --no-wall emergency
		+	systemctl isolate emergency.target
		+	<bash/>

← Older revision		Revision as of 09:23, 7 January 2015
Line 44:		Line 44:
	\| Shut down and reboot the system		\| Shut down and reboot the system
	\|}		\|}
		+
		+
		+	== Old and New Commands ==
		+
		+	{\| class="wikitable"
		+	!colspan="6"\| Comparison of SysV init commands
		+	\|-
		+	\| Old Command
		+	\| New Command
		+	\| Description
		+	\|-
		+	\|runlevel
		+	\|systemctl list-units -- type target
		+	\|List currently loaded target units
		+	\|-
		+	\|telinit ''runlevel''
		+	\|systemctl isolate name.target
		+	\| Changes the current target
		+	\|-
		+	\|}
		+
		+	== Viewing the default target ==
		+
		+	<syntaxhighlight>
		+	systemctl get default
		+	</syntaxhighlight>
		+
		+	== Change the default target ==
		+
		+	Previously this would have be done by changing the run level in /etc/inittab
		+
		+	<syntaxhighlight>
		+	systemctl set-default name.target
		+	</syntaxhighlight>

← Older revision		Revision as of 09:18, 7 January 2015
Line 1:		Line 1:
−	== Previously and Now... ==	+	== Previously and Now.. ==
		+
		+	In the old versions of Redhat services that used the SysV or upstart, implemented in a predifined set of run levels that each represented a specific mode of operation. The run levels were numbered from 0-6.
		+
		+	Runlevels have now been replaced with the concept of systemd targets. Each target is represented by a target unit, which end with the .target file extension.
		+
		+	Targets units only purpose is to group together other systemd units, using dependencies. As an example the graphical.target unit is used to start a graphical session, starts the GNOME display Manager (gdm-service).
		+
		+	Redhat7 has a number of predefined targets which are more or less equivalent to the runlevels of RHEL6. To make life easier there a aliases set up to reflect this.
		+
		+	{\| class="wikitable"
		+	!colspan="6"\| Comparison of SysV runlevels with systemd targets
		+	\|-
		+	\| Run Level
		+	\| Target Units
		+	\| Description
		+	\|-
		+	\|0
		+	\|runlevel0.target <br/> poweroff.target
		+	\|Shutdown the system and power off the system
		+	\|-
		+	\|1
		+	\|runlevel1.target <br/> rescue.target
		+	\| Set up a resuce shell
		+	\|-
		+	\|2
		+	\|runlevel2.target <br/> multi-user.target
		+	\| Set up a non-graphical multi-user system
		+	\|-
		+	\|3
		+	\|runlevel3.target <br/> multi-user.target
		+	\| Set up a non-graphical multi-user system
		+	\|-
		+	\|4
		+	\|runlevel4.target <br/> multi-user.target
		+	\| Set up a non-graphical multi-user system
		+	\|-
		+	\|5
		+	\|runlevel5.target <br/> graphical.target
		+	\| Set up a graphical multi-user system
		+	\|-
		+	\|6
		+	\|runlevel6.target <br/> reboot.target
		+	\| Shut down and reboot the system
		+	\|}