Systemd
- systemd
- wikipedia systemd
- systemd.unit
- systemctl manpage
- How To Use Systemctl to Manage Systemd Services and Units
- 配置目录
/etc/systemd/system/docker.service.d/*.conf/etc/systemd/system//lib/systemd/system/
- 参考
# 查看配置
systemctl show docker
# 修改 Service 需要重载
systemctl daemon-reload
# 查看定义的配置
systemctl show --property=Environment docker
# 重启服务
systemctl restart docker
systemctl list-units --all
systemctl list-units --type=service
systemctl list-unit-files
# 查看 service 文件
systemctl cat docker.service
# 查看依赖
systemctl list-dependencies sshd.service
# mask 后的服务不能被启动
systemctl mask nginx.service
systemctl unmask nginx.service
# 编辑 service 文件
systemctl edit nginx.service
# 编辑完整的文件,而不是一个片段,会生成部分内容
systemctl edit --full nginx.service
# 系统状态
systemctl status
# 服务状态
systemctl status prometheus-node-exporter.service
# 远程服务状态
systemctl -H [email protected] status httpd.service
# is-active, is-failed, is-enabled
systemctl is-active prometheus-node-exporter.service
# 管理
# start stop restart kill reload show
systemctl start apache.service
# 查看属性
systemctl show -P CPUShare apache.service
# 设置属性
systemctl set-property httpd.service CPUShares=500
#
systemctl daemon-reload
# 查看依赖
# --all - 所有
systemctl list-dependencies nginx.service
# enabled disabled static masked
# static - 无 [Install]， 只能被依赖
# masked - 被禁止
systemctl list-unit-files --type=service
# 查看内容
systemctl cat atd.service
| command | mean |
|---|---|
| 查询 | - |
| systemctl list-dependencies | unit 依赖 |
| systemctl list-sockets | sockets 状态 |
| systemctl list-jobs | 活跃 jobs |
| systemctl list-unit-files | unit 文件和状态 |
| systemctl list-units | units loaded/active |
| systemctl get-default | default target (like run level) |
| 服务 | - |
| systemctl stop service | 停止 |
| systemctl start service | 启动 |
| systemctl restart service | 重启 |
| systemctl reload service | 配置重载 |
| systemctl daemon-reload | 重载 unit 文件 |
| systemctl status service | 服务状态 |
| systemctl --failed | 失败的服务 |
| systemctl reset-failed | 重置失败的状态 |
| systemctl enable service | 服务自启动 |
| systemctl disable service | 关闭自启动 |
| systemctl show service | 服务信息 |
| systemctl edit service | 编辑 unit |
| systemctl edit --full service | 编辑服务 |
| systemctl -H host status network | 远程执行 |
| 系统状态 | - |
| systemctl reboot | 重启 / reboot.target |
| systemctl poweroff | 关机 / poweroff.target |
| systemctl emergency | emergency.target |
| systemctl default | 恢复到默认 multi-user.target |
| 日志 | - |
| journalctl | 所有日志 |
| journalctl -u network.service | 网络服务日志 |
| journalctl -f | 跟随显示 |
| journalctl -k | 内核日志 |
| util | desc |
|---|---|
| systemctl | 主要命令 |
| journalctl | |
| notify | |
| systemd-analyze | 查看启动耗时 |
| cgls | |
| cgtop | |
| loginctl | 当前登陆用户 |
| nspwan | |
| hostnamectl | 查看和管理主机信息 |
| localectl | 本地化配置 |
| timedatectl | 时区 |
| daemon | desc |
|---|---|
| systemd | |
| journald | |
| networkd | |
| logind | |
| user session |
| unit | desc |
|---|---|
| Service | 系统服务 |
| Target | 多个 Unit 构成的一个组 |
| Device | 硬件设备 |
| Mount | 文件系统的挂载点 |
| Automount | 自动挂载点 |
| Path | 文件或路径 |
| Scope | 不是由 Systemd 启动的外部进程 |
| Slice | 进程组 |
| Snapshot | Systemd 快照，可以切回某个快照 |
| Socket | 进程间通信的 socket |
| Swap | swap 文件 |
| Timer | 定时器 |
Unit 文件
[Unit]
Description=描述
Documentation=文档地址
Requires=强依赖 Unit
Wants=弱依赖 Unit
BindsTo=添加依赖到 Unit - 指定 Unit 退出则当前 Unit 会退出
Before=
After=
Conflicts=不能同时运行 Unit
Condition=
Assert=
[Install]
WantedBy=指定 Target 会 link 到 /etc/systemd/system/<Target>.wants
RequiredBy=指定 Target 会 link 到 /etc/systemd/system/<Target>.required
Alias=
Also=同时启动其他 Unit
[Service]
# simple - 执行 ExecStart
# forking
# oneshot - 一次性，执行完成后继续
# dbus - 通过 DBus 启动
# notify - 执行完毕通知 systemd
# idle - 有其他任务当前任务才执行
Type=simple
ExecStart=
ExecStartPre=
ExecStartPost=
ExecReload=
ExecStop=
ExecStopPost=
RestartSec=
# 重启情况 - always, on-success, on-failure, on-abnormal, on-abort, on-watchdog
Restart=
TimeoutSec=
Environment=
Target
Unit 组, 类似于其他 init 的 runlevel 概念
| runlevel | target name | link |
|---|---|---|
| Runlevel 0 | runlevel0.target | poweroff.target |
| Runlevel 1 | runlevel1.target | rescue.target |
| Runlevel 2 | runlevel2.target | multi-user.target |
| Runlevel 3 | runlevel3.target | multi-user.target |
| Runlevel 4 | runlevel4.target | multi-user.target |
| Runlevel 5 | runlevel5.target | graphical.target |
| Runlevel 6 | runlevel6.target | reboot.target |
# 查看当前系统的所有 Target
systemctl list-unit-files --type=target
# 查看一个 Target 包含的所有 Unit
systemctl list-dependencies multi-user.target
# 查看启动时的默认 Target
systemctl get-default
# 设置启动时的默认 Target
sudo systemctl set-default multi-user.target
# 切换 Target 时，默认不关闭前一个 Target 启动的进程，
# systemctl isolate 命令改变这种行为，
# 关闭前一个 Target 里面所有不属于后一个 Target 的进程
sudo systemctl isolate multi-user.target
Target vs init/RunLevel
- init/RunLevel
- 默认 RunLevel /etc/inittab
- 脚本位于 /etc/init.d - 等同于 Unit
- 启动的脚本 link 到 /etc/rc.d 或 /etc/runlevels/
- init 配置位于
/etc/sysconfig或/etc/rc.conf
- Target
- 默认 /etc/systemd/system/default.target
- link 到 multi-user.target 或 graphical.target
- Unit 位于 /lib/systemd/system
- 启动后位于 /etc/systemd/system
- systemd 配置 /lib/systemd, /etc/systemd
- 默认 /etc/systemd/system/default.target
Example
/etc/systemd/system/prometheus-node-exporter.service
[Unit]
Description=Prometheus Node Exporter
After=network-online.target
[Service]
# User=prometheus
Restart=on-failure
ExecStart=/opt/prometheus/bin/node_exporter
FAQ
Why archlinux migrate to systemd
- Archlinux is moving to systemd - 2012-08
查看开启的服务
systemctl list-unit-files --state=enabled
systemctl list-unit-files --state=enabled --type=service
systemctl list-unit-files | grep enabled
crontab
- /var/spool/cron/root - 全局，无用户
- /etc/crontab - root，需要指定用户
- /etc/cron.d/ - 需要指定用户