13个systemd与systemctl命令详解(linux)
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服务的CPU利用率(分配额)
25. 获取当前某个服务的CPU分配额(如httpd)
# systemctl show -p CPUShares httpd.service CPUShares=1024
注意:各个服务的默认CPU分配份额=1024,你可以增加/减少某个进程的CPU分配份额。
26. 将某个服务(httpd.service)的CPU分配份额限制为2000 CPUShares/
# systemctl set-property httpd.service CPUShares=2000 # systemctl show -p CPUShares httpd.service CPUShares=2000
注意:当你为某个服务设置CPUShares,会自动创建一个以服务名命名的目录(如 httpd.service),里面包含了一个名为90-CPUShares.conf的文件,该文件含有CPUShare限制信息,你可以通过以下方式查看该文件:
# vi /etc/systemd/system/httpd.service.d/90-CPUShares.conf [Service] CPUShares=2000
27. 检查某个服务的所有配置细节
# systemctl show httpd Id=httpd.service Names=httpd.service Requires=basic.target Wants=system.slice WantedBy=multi-user.target Conflicts=shutdown.target Before=shutdown.target multi-user.target After=network.target remote-fs.target nss-lookup.target systemd-journald.socket basic.target system.slice Description=The Apache HTTP Server LoadState=loaded ActiveState=active SubState=running FragmentPath=/usr/lib/systemd/system/httpd.service ....
28. 分析某个服务(httpd)的关键链
# systemd-analyze critical-chain httpd.service The time after the unit is active or started is printed after the "@" character. The time the unit takes to start is printed after the "+" character. httpd.service +142ms └─network.target @11.168s └─network.service @9.456s +1.712s └─NetworkManager.service @8.858s +596ms └─firewalld.service @4.931s +3.926s └─basic.target @4.916s └─sockets.target @4.916s └─dbus.socket @4.916s └─sysinit.target @4.905s └─systemd-update-utmp.service @4.864s +39ms └─auditd.service @4.563s +301ms └─systemd-tmpfiles-setup.service @4.485s +69ms └─rhel-import-state.service @4.342s +142ms └─local-fs.target @4.324s └─boot.mount @4.286s +31ms └─[email protected]\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.service @4.092s +149ms └─dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.device @4.092s
29. 获取某个服务(httpd)的依赖性列表
# systemctl list-dependencies httpd.service httpd.service ├─system.slice └─basic.target ├─firewalld.service ├─microcode.service ├─rhel-autorelabel-mark.service ├─rhel-autorelabel.service ├─rhel-configure.service ├─rhel-dmesg.service ├─rhel-loadmodules.service ├─paths.target ├─slices.target │ ├─-.slice │ └─system.slice ├─sockets.target │ ├─dbus.socket ....
30. 按等级列出控制组
# systemd-cgls ├─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 23 ├─user.slice │ └─user-0.slice │ └─session-1.scope │ ├─2498 sshd: [email protected]/0 │ ├─2500 -bash │ ├─4521 systemd-cgls │ └─4522 systemd-cgls └─system.slice ├─httpd.service │ ├─4440 /usr/sbin/httpd -DFOREGROUND │ ├─4442 /usr/sbin/httpd -DFOREGROUND │ ├─4443 /usr/sbin/httpd -DFOREGROUND │ ├─4444 /usr/sbin/httpd -DFOREGROUND │ ├─4445 /usr/sbin/httpd -DFOREGROUND │ └─4446 /usr/sbin/httpd -DFOREGROUND ├─polkit.service │ └─721 /usr/lib/polkit-1/polkitd --no-debug ....
31. 按CPU、内存、输入和输出列出控制组
# systemd-cgtop Path Tasks %CPU Memory Input/s Output/s / 83 1.0 437.8M - - /system.slice - 0.1 - - - /system.slice/mariadb.service 2 0.1 - - - /system.slice/tuned.service 1 0.0 - - - /system.slice/httpd.service 6 0.0 - - - /system.slice/NetworkManager.service 1 - - - - /system.slice/atop.service 1 - - - - /system.slice/atopacct.service 1 - - - - /system.slice/auditd.service 1 - - - - /system.slice/crond.service 1 - - - - /system.slice/dbus.service 1 - - - - /system.slice/firewalld.service 1 - - - - /system.slice/lvm2-lvmetad.service 1 - - - - /system.slice/polkit.service 1 - - - - /system.slice/postfix.service 3 - - - - /system.slice/rsyslog.service 1 - - - - /system.slice/system-getty.slice/[email protected] 1 - - - - /system.slice/systemd-journald.service 1 - - - - /system.slice/systemd-logind.service 1 - - - - /system.slice/systemd-udevd.service 1 - - - - /system.slice/webmin.service 1 - - - - /user.slice/user-0.slice/session-1.scope 3 - - - -
控制系统运行等级
32. 启动系统救援模式
# systemctl rescue Broadcast message from [email protected] on pts/0 (Wed 2015-04-29 11:31:18 IST): The system is going down to rescue mode NOW!
33. 进入紧急模式
# systemctl emergency Welcome to emergency mode! After logging in, type "journalctl -xb" to view system logs, "systemctl reboot" to reboot, "systemctl default" to try again to boot into default mode.
34. 列出当前使用的运行等级
# systemctl get-defaul tmulti-user.target
35. 启动运行等级5,即图形模式
# systemctl isolate runlevel5.target 或 # systemctl isolate graphical.target
36. 启动运行等级3,即多用户模式(命令行)
# systemctl isolate runlevel3.target 或 # systemctl isolate multiuser.target
36. 设置多用户模式或图形模式为默认运行等级
# systemctl set-default runlevel3.target # systemctl set-default runlevel5.target
37. 重启、停止、挂起、休眠系统或使系统进入混合睡眠
# systemctl reboot # systemctl halt # systemctl suspend # systemctl hibernate # systemctl hybrid-sleep
对于不知运行等级为何物的人,说明如下。
运行级别 0 : 关闭系统
运行级别 1 : 救援?维护模式
运行级别 3 : 多用户,无图形系统
运行级别 4 : 多用户,无图形系统
运行级别 5 : 多用户,图形化系统
运行级别 6 : 关闭并重启机
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