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Quick Docs PR #313 part 1: debug systemd

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= How to debug systemd problems
Caleb McKee; Petr Bokoc; Peter Boy
:revnumber: F32
:revdate: 2020-04-10
:category: Troubleshooting
:tags: systemd
'''
If you are experiencing a problem with system boot-up due to xref:understanding-and-administering-systemd.adoc[systemd], please see the link:Bugs/Common[commonbugs] document before filing a bug. Some easy configuration tweaks that fix a wide range of issues may be listed there. If the problem you are seeing is not listed there or none of the workarounds seem to help, please consider filing a bug to help us make Fedora run better on your hardware.
[IMPORTANT]
======
[TIP]
====
Have a look at the upstream project's link:http://freedesktop.org/wiki/Software/systemd/Debugging[helpful documentation] on the topic.
====
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======
'''
include::{partialsdir}/unreviewed-message.adoc[]
*Foreword*
If you are experiencing a problem with system boot up due to systemd,
please see the link:Bugs/Common[common bugs] document before filing a
bug. Some easy configuration tweaks that fix a wide range of issues may
be listed there. If the problem you are seeing is not listed there or
none of the workarounds seem to help, please consider filing a bug to
help us make Fedora run better on your hardware.
[[debugging-systemd-problems]]
Debugging systemd problems
--------------------------
[[various-useful-systemd-related-commands]]
Various useful systemd related commands
---------------------------------------
== Various useful systemd related commands
* Run `systemctl list-jobs`
* List all jobs that are "running" or "waiting". This command can be used to identify causes of a slow boot. The boot process waits for "running" jobs to complete. Jobs listed as "waiting" will only be executed after "running" jobs have completed.
+
[source,bash]
----
[…]# systemctl list-jobs
----
To identify slow boot and look for the jobs that are "running" those
jobs are the ones where boot waits for completion on and the ones that
listed as "waiting" will be executed only after those which are
"running" are completed.
* List all available services and their current status
+
[source,bash]
----
[…]# systemctl list-units -t service --all
----
* Run `systemctl list-units -t service --all`
To list all available services and their current status
* Show all active services
+
[source,bash]
----
[…]# systemctl list-units -t service
----
* Run `systemctl list-units -t service`
To show all active services
* Examine the current runtime status of a service. (In this example the ssh service)
+
[source,bash]
----
[…]# systemctl status sshd.service
----
* Run `systemctl status sshd.service`
To examine the current runtime status of a service. (In the above
example the ssh service)
* Show all available targets.
+
[source,bash]
----
[…]# systemctl list-units -t target --all
----
* Run `systemctl list-units -t target --all`
To show all available targets.
* Show all active targets.
+
[source,bash]
----
[…]# systemctl list-units -t target
----
* Run `systemctl list-units -t target`
To show all active targets.
* Run `systemctl show -p "Wants" multi-user.target`
To see which services a target pulls in. ( In the above example the
* Display which services a target pulls in. ( In this example the
multi-user.target )
+
[source,bash]
----
[…]# systemctl show -p "Wants" multi-user.target
----
* Run
`/usr/lib/systemd/systemd --test --system --unit=multi-user.target`
To examine what gets started when when booted into a specific target. (
In the above example the multi-user.target )
* Examine what gets started when booted into a specific target. (in this example the multi-user.target)
+
[source,bash]
----
[…]# /usr/lib/systemd/systemd --test --system --unit=multi-user.target
----
[[systemd-boot-parameters]]
systemd boot parameters
-----------------------
== Various useful systemd boot parameters
The following boot parameters are also available to further assist with
debugging boot issues.
systemd.unit= : Overrides the unit to activate on boot. This may be used
to temporarily boot into a different boot unit, for example
rescue.target or emergency.target. ( Defaults to default.target. )::
systemd.unit=:: Overrides the unit to activate on boot. This may be used to temporarily boot into a different boot unit, for example `rescue.target` or `emergency.target`. Defaults to `default.target`.
systemd.dump_core= : Takes a boolean argument. If true systemd dumps
core when it crashes. Otherwise no core dump is created. ( Defaults to
true )::
systemd.dump_core=:: Takes a boolean argument. If true, systemd dumps the core when it crashes. Otherwise no core dump is created. Defaults to true.
systemd.crash_shell= : Takes a boolean argument. If true systemd spawns
a shell when it crashes. Otherwise no core dump is created. Defaults to
false, for security reasons, as the shell is not protected by any
password authentication.::
systemd.crash_shell=:: Takes a boolean argument. If true, systemd spawns a shell when it crashes. Otherwise no core dump is created. Defaults to false, for security reasons, as the shell is not protected by any password authentication.
systemd.crash_chvt= :Takes an integer argument. If positive systemd
activates the specified virtual terminal when it crashes. ( Defaults to
-1 )::
systemd.crash_chvt=:: Takes an integer argument. If positive, systemd activates the specified virtual terminal when it crashes. Defaults to -1.
systemd.confirm_spawn= : Takes a boolean argument. If true asks for
confirmation when spawning processes. ( Defaults to false )::
systemd.confirm_spawn=:: Takes a boolean argument. If true, asks for confirmation when spawning processes. Defaults to false.
systemd.show_status= : Takes a boolean argument. If true shows terse
service status updates on the console during bootup. ( Defaults to true
)::
systemd.show_status=:: Takes a boolean argument. If true, shows terse service status updates on the console during bootup. Defaults to true.
systemd.sysv_console= : Takes a boolean argument. If true output of SysV
init scripts will be directed to the console. ( Defaults to true, unless
quiet is passed as kernel command line option in which case it defaults
to false. )::
systemd.sysv_console=:: Takes a boolean argument. If true, output of SysV init scripts will be directed to the console. Defaults to true, unless quiet is passed as kernel command line option in which case it defaults to false.
systemd.log_target= : Set log target. Argument must be one of console,
syslog, kmsg, syslog-or-kmsg, null.::
systemd.log_target=:: Sets the log target. Argument must be console, syslog, kmsg, yslog-or-kmsg, or null.
systemd.log_level= : Set log level. As argument this accepts a numerical
log level or the well-known syslog symbolic names (lowercase): emerg,
alert, crit, err, warning, notice, info, debug.::
systemd.log_level=:: Sets the log level. This command accepts a numerical log level or the well-known syslog symbolic names (lowercase): emerg, alert, crit, err, warning, notice, info, debug as an argument.
systemd.log_color= : Highlight important log messages. Argument is a
boolean value. If the argument is omitted it defaults to true.::
systemd.log_color=:: Highlights important log messages. Argument is a boolean value. If the argument is omitted, it defaults to true.
systemd.log_location= : Include code location in log messages. This is
mostly relevant for debugging purposes. Argument is a boolean value. If
the argument is omitted it defaults to true.::
systemd.log_location=:: Includes code location in log messages. This is mostly relevant for debugging purposes. Argument is a boolean value. If the argument is omitted it defaults to true.
Category:Debugging[D] Category:How_to[Category:How to]
'''
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