systemd man 信息

systemd較為復雜，在崇尚簡潔高效的Unix/Linux系統風格下存在爭議！systemd的Man信息
https://manpages.debian.org/testing/systemd/index.html

systemd由來

因為Linux系統啟動以往使用init進程，存在啟動時間長問題，原因是init進程屬于串行啟動，只有當前一個進程啟動完成后才啟動下一個進程；再者init腳本在系統功能越來越復雜的背景下必然越來越復雜冗長，在對于系統維護以及簡化系統等迫切需求下出現了systemd！

systemd簡述

Systemd(System Daemon) - 系統啟動以及管理的系統守護進程。Systemd功能強大，使用方便，但正如Man信息顯示的一樣相關命令機器使用較為復雜，違反了Unix/Linux的Keep simple, keep stupid設計原則!

systemd 系統管理

Systemd 管理系統命令systemctl

systemctl [OPTIONS...] COMMAND ...

Query or send control commands to the system manager.

Unit Commands:
list-units [PATTERN...] List units currently in memory
list-sockets [PATTERN...] List socket units currently in memory,
ordered by address
list-timers [PATTERN...] List timer units currently in memory,
ordered by next elapse
is-active PATTERN... Check whether units are active
is-failed PATTERN... Check whether units are failed
status [PATTERN...|PID...] Show runtime status of one or more units
show [PATTERN...|JOB...] Show properties of one or more
units/jobs or the manager
cat PATTERN... Show files and drop-ins of specified units
help PATTERN...|PID... Show manual for one or more units
list-dependencies [UNIT...] Recursively show units which are required
or wanted by the units or by which those
units are required or wanted
start UNIT... Start (activate) one or more units
stop UNIT... Stop (deactivate) one or more units
reload UNIT... Reload one or more units
restart UNIT... Start or restart one or more units
try-restart UNIT... Restart one or more units if active
reload-or-restart UNIT... Reload one or more units if possible,
otherwise start or restart
try-reload-or-restart UNIT... If active, reload one or more units,
if supported, otherwise restart
isolate UNIT Start one unit and stop all others
kill UNIT... Send signal to processes of a unit
clean UNIT... Clean runtime, cache, state, logs or
configuration of unit
freeze PATTERN... Freeze execution of unit processes
thaw PATTERN... Resume execution of a frozen unit
set-property UNIT PROPERTY=VALUE... Sets one or more properties of a unit
service-log-level SERVICE [LEVEL] Get/set logging threshold for service
service-log-target SERVICE [TARGET] Get/set logging target for service
reset-failed [PATTERN...] Reset failed state for all, one, or more
units
Unit File Commands:
list-unit-files [PATTERN...] List installed unit files
enable [UNIT...|PATH...] Enable one or more unit files
disable UNIT... Disable one or more unit files
reenable UNIT... Reenable one or more unit files
preset UNIT... Enable/disable one or more unit files
based on preset configuration
preset-all Enable/disable all unit files based on
preset configuration
is-enabled UNIT... Check whether unit files are enabled
mask UNIT... Mask one or more units
unmask UNIT... Unmask one or more units
link PATH... Link one or more units files into
the search path
revert UNIT... Revert one or more unit files to vendor
version
add-wants TARGET UNIT... Add 'Wants' dependency for the target
on specified one or more units
add-requires TARGET UNIT... Add 'Requires' dependency for the target
on specified one or more units
edit UNIT... Edit one or more unit files
get-default Get the name of the default target
set-default TARGET Set the default target

Machine Commands:
list-machines [PATTERN...] List local containers and host

Job Commands:
list-jobs [PATTERN...] List jobs
cancel [JOB...] Cancel all, one, or more jobs

Environment Commands:
show-environment Dump environment
set-environment VARIABLE=VALUE... Set one or more environment variables
unset-environment VARIABLE... Unset one or more environment variables
import-environment [VARIABLE...] Import all or some environment variables

Manager State Commands:
daemon-reload Reload systemd manager configuration
daemon-reexec Reexecute systemd manager
log-level [LEVEL] Get/set logging threshold for manager
log-target [TARGET] Get/set logging target for manager
service-watchdogs [BOOL] Get/set service watchdog state

System Commands:
is-system-running Check whether system is fully running
default Enter system default mode
rescue Enter system rescue mode
emergency Enter system emergency mode
halt Shut down and halt the system
poweroff Shut down and power-off the system
reboot Shut down and reboot the system
kexec Shut down and reboot the system with kexec
exit [EXIT_CODE] Request user instance or container exit
switch-root ROOT [INIT] Change to a different root file system
suspend Suspend the system
hibernate Hibernate the system
hybrid-sleep Hibernate and suspend the system
suspend-then-hibernate Suspend the system, wake after a period of
time, and hibernate
Options:
-h --help Show this help
--version Show package version
--system Connect to system manager
--user Connect to user service manager
-H --host=[USER@]HOST Operate on remote host
-M --machine=CONTAINER Operate on a local container
-t --type=TYPE List units of a particular type
--state=STATE List units with particular LOAD or SUB or ACTIVE state
--failed Shortcut for --state=failed
-p --property=NAME Show only properties by this name
-P NAME Equivalent to --value --property=NAME
-a --all Show all properties/all units currently in memory,
including dead/empty ones. To list all units installed
on the system, use 'list-unit-files' instead.
-l --full Don't ellipsize unit names on output
-r --recursive Show unit list of host and local containers
--reverse Show reverse dependencies with 'list-dependencies'
--with-dependencies Show unit dependencies with 'status', 'cat',
'list-units', and 'list-unit-files'.
--job-mode=MODE Specify how to deal with already queued jobs, when
queueing a new job
-T --show-transaction When enqueuing a unit job, show full transaction
--show-types When showing sockets, explicitly show their type
--value When showing properties, only print the value
-i --ignore-inhibitors When shutting down or sleeping, ignore inhibitors
--kill-who=WHO Whom to send signal to
-s --signal=SIGNAL Which signal to send
--what=RESOURCES Which types of resources to remove
--now Start or stop unit after enabling or disabling it
--dry-run Only print what would be done
Currently supported by verbs: halt, poweroff, reboot,
kexec, suspend, hibernate, suspend-then-hibernate,
hybrid-sleep, default, rescue, emergency, and exit.
-q --quiet Suppress output
--wait For (re)start, wait until service stopped again
For is-system-running, wait until startup is completed
--no-block Do not wait until operation finished
--no-wall Don't send wall message before halt/power-off/reboot
--no-reload Don't reload daemon after en-/dis-abling unit files
--no-legend Do not print a legend (column headers and hints)
--no-pager Do not pipe output into a pager
--no-ask-password Do not ask for system passwords
--global Enable/disable/mask unit files globally
--runtime Enable/disable/mask unit files temporarily until next
reboot
-f --force When enabling unit files, override existing symlinks
When shutting down, execute action immediately
--preset-mode= Apply only enable, only disable, or all presets
--root=PATH Enable/disable/mask unit files in the specified root
directory
-n --lines=INTEGER Number of journal entries to show
-o --output=STRING Change journal output mode (short, short-precise,
short-iso, short-iso-precise, short-full,
short-monotonic, short-unix,
verbose, export, json, json-pretty, json-sse, cat)
--firmware-setup Tell the firmware to show the setup menu on next boot
--boot-loader-menu=TIME
Boot into boot loader menu on next boot
--boot-loader-entry=NAME
Boot into a specific boot loader entry on next boot
--plain Print unit dependencies as a list instead of a tree
--timestamp=FORMAT Change format of printed timestamps.
'pretty' (default): 'Day YYYY-MM-DD HH:MM:SS TZ
'us': 'Day YYYY-MM-DD HH:MM:SS.UUUUUU TZ
'utc': 'Day YYYY-MM-DD HH:MM:SS UTC
'us+utc': 'Day YYYY-MM-DD HH:MM:SS.UUUUUU UTC

See the systemctl(1) man page for details.

hostnamectl

hostnamectl -- 顯示當前設備的信息
也可以使用
sudo hostnamectl set-hostname xxxx -- 設置主機名
localectl [OPTIONS...] COMMAND ...

Query or change system locale and keyboard settings.

Commands:
status Show current locale settings
set-locale LOCALE... Set system locale
list-locales Show known locales
set-keymap MAP [MAP] Set console and X11 keyboard mappings
list-keymaps Show known virtual console keyboard mappings
set-x11-keymap LAYOUT [MODEL [VARIANT [OPTIONS]]]
Set X11 and console keyboard mappings
list-x11-keymap-models Show known X11 keyboard mapping models
list-x11-keymap-layouts Show known X11 keyboard mapping layouts
list-x11-keymap-variants [LAYOUT]
Show known X11 keyboard mapping variants
list-x11-keymap-options Show known X11 keyboard mapping options

Options:
-h --help Show this help
--version Show package version
--no-pager Do not pipe output into a pager
--no-ask-password Do not prompt for password
-H --host=[USER@]HOST Operate on remote host
-M --machine=CONTAINER Operate on local container
--no-convert Don't convert keyboard mappings

See the localectl(1) man page for details

localectl

localectl -- 永遠忽查看本地化設置
localectl [OPTIONS...] COMMAND ...

Query or change system locale and keyboard settings.

Commands:
status Show current locale settings
set-locale LOCALE... Set system locale
list-locales Show known locales
set-keymap MAP [MAP] Set console and X11 keyboard mappings
list-keymaps Show known virtual console keyboard mappings
set-x11-keymap LAYOUT [MODEL [VARIANT [OPTIONS]]]
Set X11 and console keyboard mappings
list-x11-keymap-models Show known X11 keyboard mapping models
list-x11-keymap-layouts Show known X11 keyboard mapping layouts
list-x11-keymap-variants [LAYOUT]
Show known X11 keyboard mapping variants
list-x11-keymap-options Show known X11 keyboard mapping options

Options:
-h --help Show this help
--version Show package version
--no-pager Do not pipe output into a pager
--no-ask-password Do not prompt for password
-H --host=[USER@]HOST Operate on remote host
-M --machine=CONTAINER Operate on local container
--no-convert Don't convert keyboard mappings

See the localectl(1) man page for details

timedatectl

timedatectl -- 查看當前時區設置
timedatectl [OPTIONS...] COMMAND ...

Query or change system time and date settings.

Commands:
status Show current time settings
show Show properties of systemd-timedated
set-time TIME Set system time
set-timezone ZONE Set system time zone
list-timezones Show known time zones
set-local-rtc BOOL Control whether RTC is in local time
set-ntp BOOL Enable or disable network time synchronization

systemd-timesyncd Commands:
timesync-status Show status of systemd-timesyncd
show-timesync Show properties of systemd-timesyncd

Options:
-h --help Show this help message
--version Show package version
--no-pager Do not pipe output into a pager
--no-ask-password Do not prompt for password
-H --host=[USER@]HOST Operate on remote host
-M --machine=CONTAINER Operate on local container
--adjust-system-clock Adjust system clock when changing local RTC mode
--monitor Monitor status of systemd-timesyncd
-p --property=NAME Show only properties by this name
-a --all Show all properties, including empty ones
--value When showing properties, only print the value

See the timedatectl(1) man page for details.

loginctl

loginctl -- 查看當前登錄的用戶
timedatectl [OPTIONS...] COMMAND ...

Query or change system time and date settings.

Commands:
status Show current time settings
show Show properties of systemd-timedated
set-time TIME Set system time
set-timezone ZONE Set system time zone
list-timezones Show known time zones
set-local-rtc BOOL Control whether RTC is in local time
set-ntp BOOL Enable or disable network time synchronization

systemd-timesyncd Commands:
timesync-status Show status of systemd-timesyncd
show-timesync Show properties of systemd-timesyncd

Options:
-h --help Show this help message
--version Show package version
--no-pager Do not pipe output into a pager
--no-ask-password Do not prompt for password
-H --host=[USER@]HOST Operate on remote host
-M --machine=CONTAINER Operate on local container
--adjust-system-clock Adjust system clock when changing local RTC mode
--monitor Monitor status of systemd-timesyncd
-p --property=NAME Show only properties by this name
-a --all Show all properties, including empty ones
--value When showing properties, only print the value

See the timedatectl(1) man page for details.