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linux:systemd [2015/10/15 13:02] – niziaklinux:systemd [2017/05/16 08:53] – [info/status] niziak
Line 16: Line 16:
  
 <code bash> <code bash>
 +systemd-analyze blame
 systemd-analyze critical-chain systemd-analyze critical-chain
 +systemd-analyze critical-chain  network.service
 +systemctl list-dependencies network.service
 systemctl --failed systemctl --failed
 </code> </code>
  
 +<code bash>
 +systemd-cgtop
 +</code>
  
 ==== emergency mode  ==== ==== emergency mode  ====
Line 42: Line 48:
 <code>setenv bootargs ${bootargs} systemd.unit=emergency.target</code> <code>setenv bootargs ${bootargs} systemd.unit=emergency.target</code>
  
-=== Start service when MMC card is inserted ===+Enable debug console on tty9 
 +<code bash>systemctl enable debug-shell.service</code> 
 + 
 +==== Start service when MMC card is inserted ====
 Create directory "dev-mmcblk0.device.wants" and put symlink to service inside it. Create directory "dev-mmcblk0.device.wants" and put symlink to service inside it.
 List of devices: <code bash>systemctl --all --full -t device</code> List of devices: <code bash>systemctl --all --full -t device</code>
Line 70: Line 79:
  
 === [Unit] === === [Unit] ===
 +  * Requires  - units listed here, are also activated with unit. If any start fail, this unit will be not activated.
 +  * Conflicts - negative dependencies, opposite to Requires
 +
   * Requisite - similar to require, but if not met, service will be not started (fail immediately). Usefull to perform action when removable device is inserted.    * Requisite - similar to require, but if not met, service will be not started (fail immediately). Usefull to perform action when removable device is inserted. 
   * Requisite=!local-fs.target   * Requisite=!local-fs.target
 +
   * BindsTo - similar to require, but also declares to stop unit when other units dissapers (aslo nice for removable devices handling)   * BindsTo - similar to require, but also declares to stop unit when other units dissapers (aslo nice for removable devices handling)
 +  * PartOf - stops/starts unit when unit listed is stopped/started
 +
   * After - start service after other services are started completely.   * After - start service after other services are started completely.
 +  * Before
 +
  
 === [Service] === === [Service] ===
 +  * Type
 +    * Type=simple  - default -
 +    * Type=forking - process will spawn child and exit. Child should live as daemon.
 +      * PIDFile=/var/run/service.pid - set it to give systemd possibility to known forked child PID
 +    * Type=oneshot - process should exit. Systemd is not waiting for finish. Like batch file.
 +      * usefull for setup some things, not starting daemons. See ''ReamainAfterExit=Yes'')
 +      * Multiple ExecStart= allowed, and will be executed sequentially
 +    * Type=dbus    - systemd assume process started when process name connects to D-Bus
 +    * Type=notify  - systemd assume process started when process explicitly notify systemd using ''sd_notify()''
 +    * Type=idle
 +
 +
 +  * ExecStart= - first argument MUST be full path to executable
 +    * ExecStart=-/bin/false   - minus sign = ignore exit code and assume always success
 +    * Multple ExecStart= are allowed, and executed sequentially. If one command fails, other lines are not executed and unit is failed.
 +  * ExecStartPre= - ''ExecStart='' will run only if all ''ExecStartPre='' command exits with success. May not to start long processes.
 +  * ExecStartPost= - will be executed only if service has started successfully
 +  * ExecStop=
 +  * ExecReload=
 +
   * Nice=-20   * Nice=-20
   * IOSchedulingClass=0   * IOSchedulingClass=0
   * IOSchedulingPriority=0   * IOSchedulingPriority=0
   * StandardOutput=tty |none | journal+console   * StandardOutput=tty |none | journal+console
 +
 +  * Restart=always
 +  * RestartSec=10s
 +
 +  * RemainAfterExit=Yes - keep service active status, even all process exits. usefull for ''Type=oneshot''
  
  
Line 87: Line 129:
  
 === Remove startup console clearing === === Remove startup console clearing ===
-<code> +<file | /etc/systemd/system/getty@tty1.service.d/noclear.conf>
-/etc/systemd/system/getty@tty1.service.d/noclear.conf+
  
 [Service] [Service]
 TTYVTDisallocate=no TTYVTDisallocate=no
 +</file>
 +
 +=== udev ===
 +In udev rules.d add TAG+="systemd":
 +<code>
 +SUBSYSTEM=="input", KERNEL=="event[0-9]*", ENV{ID_INPUT_TOUCHSCREEN}=="1", ATTRS{name}=="edt-ft53*", \
 +    SYMLINK+="input/lcd_sandwich_touchscreen input/touchscreen_edt", \
 +    TAG+="systemd", \
 +    OPTIONS+="link_priority=100"
 </code> </code>
 +And now device is visible from systemd:
 +<code bash>
 +systemctl -l -a
 +  dev-input-event0.device                                                                        loaded    active   plugged   /dev/input/event0
 +  dev-input-lcd_sandwich_touchscreen.device                                                      loaded    active   plugged   /dev/input/lcd_sandwich_touchscreen
 +</code>
 +You can create refer to device, e.g. create .wants directory
 +<code>/etc/systemd/system/ev-input-lcd_sandwich_touchscreen.device.wants</code>
  
 +=== udev: start service ===
 +To start service if device is inserted:
 +<file | mu.rule>
 +..., TAG+="systemd", ENV{SYSTEMD_WANTS}="netctl-auto@mywifi.service"
 +</file>
  
 +=== do not mount crypted volumes ===
 +After switching to systemd by command <code bash>apt-get install systemd-sysv</code>, new problem occurs: 
 +system boot stops and waits for password for encrypted partition (with user data - no needed to system start).
 +
 +To prevent automount of crypted volumes, additional parameters 'noauto' and 'noearly' must be added to /etc/crypttab:
 +<file | /etc/crypttab>
 +/MyMountPoint /dev/vg_MyName/lv_MyName none luks,noauto,noearly
 +</file>
 +
 +=== Debian: Set network service timeout ===
 +System startup can hang forever if there is no link on ethernet cable:
 +<code>[    **] A start job is running for LSB: Raise network interf...38s / no limit)</code>
 +To set timeout, add file:
 +<file | /etc/systemd/system/networking.service.d/reduce-timeout.conf>
 +[Service]
 +TimeoutStartSec=15
 +</file>