linux 启动文件目录 /usr/lib/systemd/system 简介

转载已于 2023-03-23 13:20:56 修改 · 2.1k 阅读

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原文链接：https://blog.youkuaiyun.com/qq_16268979/article/details/114771258

文章标签：

#linux #mysql #服务器

于 2023-03-23 12:33:02 首次发布

文章介绍了systemd的服务管理和mysqld.service文件的详细内容，包括服务的启动、停止以及服务文件中如ExecStart、After等关键配置项的作用，强调了/etc/systemd/system/目录下自定义服务文件的重要性。

systemd有系统和用户区分：
系统（/usr/lib/systemd/system/）
用户（/etc/lib/systemd/user/）
一般系统管理员手工创建的单元文件建议存放在/etc/systemd/system/目录下面。

/usr/lib/systemd/system目录自动存放启动文件的配置位置，里面一般包含有XXXXX.service。
　当我们利用systemctl查看服务状态时，如下：

[admin@localhost system]$ systemctl status mysqld
● mysqld.service - MySQL Community Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)
   Active: active (running) since Sun 2020-05-17 13:45:54 CST; 7 months 20 days ago
  Process: 4441 ExecStartPost=/usr/bin/mysql-systemd-start post (code=exited, status=0/SUCCESS)
  Process: 4425 ExecStartPre=/usr/bin/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
 Main PID: 4440 (mysqld_safe)
   Memory: 6.6G
   CGroup: /system.slice/mysqld.service
           ├─4440 /bin/sh /usr/bin/mysqld_safe --basedir=/usr
           └─4702 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --log-error=/var/log/mysqld.log --pid-file=/var/run/mysq...

如上出现的/usr/lib/systemd/system/mysqld.service，其实我们用systemctl命令操作mysqld服务其实就是操作mysql.service文件，其实上面命令中的mysqld也可以用mysqld.service，调用该文件即可启动该服务。

mysqld.service文件内容：

[admin@localhost system]$ cat mysqld.service
#
# Simple MySQL systemd service file
#
# systemd supports lots of fancy features, look here (and linked docs) for a full list: 
#   http://www.freedesktop.org/software/systemd/man/systemd.exec.html
#
# Note: this file ( /usr/lib/systemd/system/mysql.service )
# will be overwritten on package upgrade, please copy the file to 
#
#  /etc/systemd/system/mysql.service 
#  
# to make needed changes.
# 
# systemd-delta can be used to check differences between the two mysql.service files.
#

[Unit]
Description=MySQL Community Server
After=network.target
After=syslog.target

[Install]
WantedBy=multi-user.target
Alias=mysql.service

[Service]
User=mysql
Group=mysql

# Execute pre and post scripts as root
PermissionsStartOnly=true

# Needed to create system tables etc.
ExecStartPre=/usr/bin/mysql-systemd-start pre

# Start main service
ExecStart=/usr/bin/mysqld_safe --basedir=/usr

# Don't signal startup success before a ping works
ExecStartPost=/usr/bin/mysql-systemd-start post

# Give up if ping don't get an answer
TimeoutSec=600

Restart=always
PrivateTmp=false

具体可参考：

《linux systemd service 服务文件简介》https://blog.youkuaiyun.com/whatday/article/details/129728334