[svc]centos7的服務治理-systemd
阿新 • • 發佈：2018-03-04
pat daemon nts mis com dockerd link 硬件 ner
經常用到的高頻命令小結
- 所有服務unit放在這裏 ll /usr/lib/systemd/system - 默認啟動級別 [root@n1 ~]# ll /etc/systemd/system/default.target lrwxrwxrwx 1 root root 41 Mar 4 09:02 /etc/systemd/system/default.target -> /usr/lib/systemd/system/multi-user.target - 開機啟動的服務 ll /etc/systemd/system/multi-user.target.wants/ - 哪些服務開機會啟動 [root@n1 ~]# systemctl list-unit-files --type service |grep enable [email protected] enabled crond.service enabled docker.service enabled [email protected] enabled ntpdate.service enabled rsyslog.service enabled sshd.service enabled sysstat.service enabled - 目前哪些服務處於active狀態 [root@n1 ~]# systemctl list-units --type service |grep active crond.service loaded active running Command Scheduler dbus.service loaded active running D-Bus System Message Bus docker.service loaded active running Docker Application Container Engine [email protected] loaded active running Getty on tty1 - 查看某個服務是否開機自啟 systemctl is-enabled httpd.service 或 systemctl status httpd.service
systemd 有很多unit,其中service.unit是管理系統服務的.
unit的類型
/usr/lib/systemd/system
查看管理系統服務的相關的, 即 .service後綴的
[root@n1 system]# ls /usr/lib/systemd/system/*.service|more /usr/lib/systemd/system/arp-ethers.service /usr/lib/systemd/system/auditd.service /usr/lib/systemd/system/[email protected] /usr/lib/systemd/system/blk-availability.service /usr/lib/systemd/system/brandbot.service ... 特點: 不需要可執行權限,其內容也不能執行 僅是systemd的調用的配置文件
| unit類型 | 作用 |
|---|---|
| Service unit | 管理系統服務,我們暫且只關心這個 |
| Target unit | 多個Unit構成的一個組 |
| Device Unit | 硬件設備 |
| Mount Unit | 文件系統的掛載點 |
| Automount Unit | 自動掛載點 |
| Path Unit | 文件或路徑 |
| Scope Unit | 不是由 Systemd 啟動的外部進程 |
| Slice Unit | 進程組 |
| Snapshot Unit | Systemd 快照，可以切回某個快照 |
| Socket Unit | 進程間通信的 socket |
| Swap Unit | swap 文件 |
| Timer Unit | 定時器 |
centos6 chkconfig VS 使用systemd的service unit治理centos7服務
| 任務 | 舊指令 | 新指令 |
|---|---|---|
| 哪些服務正在跑? | chkconfig --list\grep 3:on | systemctl list-units --type=service |
| 哪些服務開機會自啟動? | chkconfig --list | systemctl list-unit-files --type=service |
| 使httpd開機自啟動 | chkconfig --level 3 httpd on | systemctl enable httpd.service |
| 使httd開機不自啟動 | chkconfig --level 3 httpd off | systemctl disable httpd.service |
| 查看httpd現在是否啟動著 | service httpd status | systemctl status httpd.service （服務詳細信息） |
| 啟動某服務 | /etc/init.d/httpd start | systemctl start httpd.service |
| 停止某服務 | /etc/init.d/httpd stop | systemctl stop httpd.service |
| 重啟某服務 | /etc/init.d/httpd restart | systemctl restart httpd.service |
| 所有已裝載的級別(而非當前級別) | runlevel | systemctl list-units --type target |
| 查看默認級別是啥 | cat /etc/inittab | systemctl get-default |
| 設置默認級別 | init 3 | systemctl set-default multi-user.target |
| 查看服務狀態 | /etc/init.d/http status | systemctl is-enabled httpd.service/systemctl status httpd.service |
| 默認啟動第一個進程 | init | systemd |
ls /usr/lib/systemd/system/*.service|more 下以service開頭的文件,都是和系統服務有關的, 其下還有別的後綴的服務.是別的unit的配置文件.
serivice unit配置
target unit: 的含義是服務組，表示一組服務。
將很多服務放在一坨, 開啟啟動時候加載這個文件.
啟動級別
/usr/lib/systemd/system
/etc/systemd/system
runlevel0.target -> poweroff.target
runlevel2.target -> multi-user.target
runlevel3.target -> multi-user.target
runlevel4.target -> multi-user.target
runlevel5.target -> graphical.target
runlevel6.target -> reboot.target註意: centos7裏,運行級別234沒區別.
查看在運行的服務
我們看ACTIVE就ok了,SUB這一列可以不用理會
[root@n1 system]# systemctl list-units --type=service
UNIT LOAD ACTIVE SUB DESCRIPTION
crond.service loaded active running Command Scheduler
dbus.service loaded active running D-Bus System Message Bus
docker.service loaded active running Docker Application Container Engine
[email protected] loaded active running Getty on tty1
httpd.service loaded active running The Apache HTTP Server查看開機是否會啟動
[root@n1 system]# systemctl list-unit-files --type=service
UNIT FILE STATE
arp-ethers.service disabled
auditd.service disabled
[email protected] enabled #開機會啟動
blk-availability.service disabled#開機不會啟動
brandbot.service static #這類不用管
conntrackd.service disabled
systemd管理服務入門
設置開機自動啟動細節
[root@n1 ~]# yum install psmisc -y
[root@n1 ~]# pstree
systemd─┬─agetty
├─crond
├─dbus-daemon
├─dockerd─┬─docker-containe─┬─docker-containe─┬─mysqld───20*[{mysqld}]
│ │ │ └─8*[{docker-containe}]
│ │ └─9*[{docker-containe}]
│ ├─docker-proxy───3*[{docker-proxy}]
│ └─11*[{dockerd}]
├─httpd───8*[httpd]
├─lvmetad
├─polkitd───5*[{polkitd}]
├─rsyslogd───2*[{rsyslogd}]
├─sshd───sshd───bash───pstree
├─systemd-journal
├─systemd-logind
└─systemd-udevd
[root@n1 system]# systemctl enable httpd
Created symlink from /etc/systemd/system/multi-user.target.wants/httpd.service to /usr/lib/systemd/system/httpd.service.相當於執行
ln -s /usr/lib/systemd/system/httpd.service /etc/systemd/system/multi-user.target.wants/httpd.servicedisable相當於刪除
[root@n1 system]# systemctl disable httpd
Removed symlink /etc/systemd/system/multi-user.target.wants/httpd.service.[root@n1 system]# ll /etc/systemd/system/multi-user.target.wants
total 0
lrwxrwxrwx. 1 root root 37 Dec 27 04:44 crond.service -> /usr/lib/systemd/system/crond.service
lrwxrwxrwx 1 root root 38 Dec 26 21:05 docker.service -> /usr/lib/systemd/system/docker.service
lrwxrwxrwx 1 root root 37 Mar 4 03:39 httpd.service -> /usr/lib/systemd/system/httpd.service
lrwxrwxrwx. 1 root root 39 Dec 26 21:00 ntpdate.service -> /usr/lib/systemd/system/ntpdate.service
lrwxrwxrwx. 1 root root 40 Dec 27 04:44 remote-fs.target -> /usr/lib/systemd/system/remote-fs.target
lrwxrwxrwx. 1 root root 39 Dec 27 04:44 rsyslog.service -> /usr/lib/systemd/system/rsyslog.service
lrwxrwxrwx. 1 root root 36 Dec 27 04:44 sshd.service -> /usr/lib/systemd/system/sshd.service
lrwxrwxrwx. 1 root root 39 Dec 27 05:00 sysstat.service -> /usr/lib/systemd/system/sysstat.service設置啟動級別的命令
- 設置默認啟動級別
[root@n1 ~]# systemctl set-default graphical.target
Removed symlink /etc/systemd/system/default.target.
Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/graphical.target.
- 查看默認的啟動級別
[root@n1 ~]# systemctl get-default
graphical.target
- 手動修改啟動級別(先將原來的rm了)
[root@n1 ~]# ln -sv /usr/lib/systemd/system/multi-user.target /etc/systemd/system/default.target
ln: failed to create symbolic link ‘/etc/systemd/system/default.target’: File exists
[root@n1 ~]# rm -rf /etc/systemd/system/default.target
[root@n1 ~]# ln -sv /usr/lib/systemd/system/multi-user.target /etc/systemd/system/default.target
‘/etc/systemd/system/default.target’ -> ‘/usr/lib/systemd/system/multi-user.target’
[root@n1 ~]# systemctl get-default
multi-user.target
- 查看服務狀態
[root@n1 ~]# systemctl is-enabled httpd.service
disabled[svc]centos7的服務治理-systemd