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--- linux_wiki:init_systems [2015/03/10 22:04]
billdozor created
+++ linux_wiki:init_systems [2019/05/25 23:50] (current)
@@ Line 6: / Line 6: @@
 **Checklist**
-  * Distro: Varies, depending upon init system.
+  * Distro(s): Varies, depending upon init system.
+----
+===== All Inits =====
+This section will compare three init systems; sysv, upstart, and systemd.
+==== Command Table ====
+  * The service name "foo" will be used in all examples.
+  * systemctl assumes ".service" appended to unit name if left off
+^ Command ^ Sysv ^ Upstart ^ Systemd ^
+| Status of Service | service foo status | initctl status foo | systemctl status foo |
+| Start Service | service foo start | initctl start foo | systemctl start foo |
+| Stop Service | service foo stop | initctl stop foo | systemctl stop foo |
+| Restart Service | service foo restart | initctl restart foo | systemctl restart foo |
+| Reload config file | service foo reload | initctl reload foo | systemctl reload foo |
+| List services | ls /etc/init.d/ | initctl list | systemctl (or)\\ systemctl list-unit-files (or)\\ systemctl list-unit-files --type=service |
+| Enable Service At Boot | chkconfig foo on | Edit /etc/init/<jobname>.conf "start on" field | systemctl enable foo |
+| Disable Service At Boot | chkconfig foo off | Edit /etc/init/<jobname>.conf "start on" field | systemctl disable foo |
+| List services and enabled run levels | chkconfig --list | initctl show-config | systemctl list-unit-files --type=service (or)\\ ls /etc/systemd/system/*.wants/ |
+----
+==== All Inits Run Levels ====
+^ Description ^ Sysv ^ Upstart ^ Systemd ^
+| Halt system | 0 | runlevel [0] | poweroff.target |
+| Single user mode | 1,s,single | runlevel [1] | rescue.target |
+| User defined. Same as 3 by default. | 2,4 | runlevel [24] | multi-user.target |
+| Multi-user, non-graphical | 3 | runlevel [3] | multi-user.target |
+| Multi-user, graphical | 5 | runlevel [5] | graphical.target |
+| Reboot | 6 | runlevel [6] | reboot.target |
+| Emergency shell | emergency | ? | emergency.target |
+  * Note: Upstart has many different "events" besides runlevels that can trigger jobs to start, such as "start on file-system" or "start on startup"
 ----
 ===== SysV Init (init) =====
+Sysv init details not contained in All Inits section.
 __Distributions__: RHEL/CentOS <= 6 (RHEL 6 uses an init/upstart combination), Debian <= 7
-==== Init run levels ====
-  * 0 : shutdown
-  * 1 and S : single user mode
-  * 2 - 5 : include networking support (GUI login can start at one of these, distro depending)
-  * 6 : reboot level
 ==== Defualt run level ====
@@ Line 29: / Line 62: @@
 ==== Master Copy of Startup Scripts ====
-/etc/init.d/
+/etc/rc.d/init.d/
 ==== rc#.d directories ====
-The rc#.d directories contain symbolic links to the scripts in /etc/init.d.
+The rc#.d directories contain symbolic links to the scripts in /etc/rc.d/init.d.
 # = the run level, ie rc0.d, rc1.d, rc2.d, rc3.d, rc4.d, rc5.d, rc6.d
@@ Line 47: / Line 80: @@
 ==== Manage Services ====
-  * chkconfig: Red Hat based systems
+  * service command: RedHat and Debian (service status/stop/start/restart)
-  * update-rc.d: Debian/Ubuntu
+  * chkconfig: Red Hat based systems (enable/disable services)
+  * update-rc.d: Debian/Ubuntu (enable/disable services)
-List all services and the run levels they will start on:
-<code bash>
-chkconfig --list
-</code>
-List a single service:
-<code bash>
-chkconfig --list httpd
-</code>
-Set a service to start on boot
-<code bash>
-chkconfig httpd on
-</code>
-==== Control Services ====
-Show service status
-<code bash>
-service httpd status
-or
-/etc/init.d/httpd status
-</code>
-Stop/start/restart a service
-<code bash>
-service httpd stop
-service httpd start
-service httpd restart
-</code>
 ----
 ===== Upstart =====
+Upstart details not contained in All Inits section.
 __Distributions__: Ubuntu 9.10 - Current (migrating to systemd), RHEL/CentOS 6 (some scripts)
 Upstart uses event driven jobs, instead of run levels to executes scripts.
-It does have events for rc0-6 to maintain comptability with init.
+It does have events for rc0-6 to maintain compatibility with init.
-==== Job Definition Files ====
+  * Job Definition Files Location: /etc/init/
+  * Job control: initctl
-  * Location: /etc/event.d/
-==== Control Jobs ====
-List all known jobs
-<code bash>
-initctl list
-</code>
-Show status of a job
-<code bash>
-initctl status httpd
-</code>
-Stop/start/restart a job
-<code bash>
-initctl stop httpd
-initctl start httpd
-initctl restart httpd
-</code>
 ----
 ===== Systemd =====
+Systemd details not contained in All Inits section.
 __Distributions__: RHEL/CentOS 7, Debian 8, Ubuntu 15.4?
@@ Line 120: / Line 108: @@
 ==== Location of Unit Scripts ====
-All of systemd unit scripts are located here (and sub folders):
+  * All of systemd unit scripts are located here (and sub folders): /usr/lib/systemd/
-<code bash>
+  * Systemd uses this directory of symlinks to run those scripts: /etc/systemd/system/
-/usr/lib/systemd/
+  * Other systemd configuration: /etc/systemd/
-</code>
+  * Unit control: systemctl
-Systemd uses this directory of symlinks to run those scripts:
-<code bash>
-/etc/systemd/system/
-</code>
-Other systemd configuration:
-<code bash>
-/etc/systemd/
-</code>
-==== Control Units ====
-List all loaded units
-<code bash>
-systemctl list-units
-or
-systemctl
-</code>
-List all loaded but inactive too
-<code bash>
-systemctl --all
-</code>
-List all installed units
-<code bash>
-systemctl list-unit-files
-</code>
-Show status of a unit
-<code bash>
-systemctl status NetworkManager.service
-or
-systemctl status NetworkManager
-</code>
-Stop/start/restart a unit
-<code bash>
-systemctl stop NetworkManager
-systemctl start NetworkManager
-systemctl restart NetworkManager
-</code>
 ==== Laptop: Disable Suspend ====