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--- linux_wiki:boot_systems_into_different_targets_manually [2016/02/29 21:22]
billdozor created
+++ linux_wiki:boot_systems_into_different_targets_manually [2019/05/25 23:50] (current)
@@ Line 3: / Line 3: @@
 **General Information**
-About this page/how-to/script.
+There are no longer runlevels; systemd uses "targets".
 ----
+===== Systemd Units =====
 Unit configuration file locations
@@ Line 11: / Line 13: @@
   * /etc/systemd/system => additional configuration files (downloaded or custom)
+\\
 Show available unit types
 <code bash>
 systemctl -t help
 </code>
+----
+===== Systemd Targets =====
 Some common targets
   * poweroff.target => power off the system
-  * emergency.target => single user (root), read only root file system, do not mount other file systems, no network.
+  * emergency.target => single user (root), root file system mounted, do not mount any other file systems, no network services.
     * Used if the system cannot be repaired in rescue.target
-  * rescue.target => single user environment (root), mount file systems read/write, with minimum services loaded. (no network)
+  * rescue.target => single user environment (root), mount local file systems, with minimum services loaded, no network services.
   * multi-user.target => Multi-user non-graphical, with all file systems and networking
   * graphical.target => GUI environment, multi-user, with all file systems and networking
   * reboot.target => reboot the system
-Current target
+\\
+What targets are currently active?
+<code bash>
+systemctl -t target
+</code>
+  * Look for either emergency, rescue, multi-user, or graphical.
+  * **Note**: If you are in the graphical target, multi-user will also be active, since multi-user is a dependency of graphical.
+\\
+Current default target
 <code bash>
 systemctl get-default
 </code>
+\\
 Set default to graphical target
 <code bash>
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 </code>
+\\
 List loaded unit files (systemctl) of type target (--type=target) whether they are active or not (--all)
 <code bash>
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   * --all => show all loaded unit files, even if they are not active
+\\
 List all installed unit files on the system
 <code bash>
@@ Line 48: / Line 67: @@
 </code>
+\\
 View a target's dependencies
 <code bash>
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   * List what will start upon entering multi-user.target
+\\
 Move from graphical target to multi-user (command prompt)
 <code bash>
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 </code>
   * Stops all GUI services, goes to command line login prompt
+----
+===== Other Systemctl Commands =====
+**Note:** By default, systemctl commands will only show the active configuration files unless you pass the "--all" option
+  * systemctl --type=service => list all loaded and active only service unit config files
+  * systemctl --type=service --all => list all loaded and active or inactive units
+  * systemctl is-active servicename => check if service is active or inactive
+  * systemctl is-enabled servicename => check if service is enabled or disabled
+  * systemctl --failed --type=service => list all failed services
+  * systemctl list-unit-files --type=service => view enabled and disabled settings for all units installed on the OS of the service type
+----
+===== Boot to rescue mode =====
+To boot to something other than the default target, such as the rescue target, during boot:
+  - Interrupt boot process at grub menu
+  - Press "e" to edit the boot entry
+  - Navigate to the "linux16" kernel entry
+  - Append "systemd.unit=rescue.target"
+  - Ctrl+x to continue boot process
 ----