How to solve the problem that Linux service cannot use system environment variables

Linux service cannot use system environment variables

Detailed description

When doing a mysql multi-instance installation before, the installation was successful, linux It can also be started successfully; however, moving support-files/mysqld_multi.server to the /etc/init.d/ directory and setting the startup (chkconfig xxx on) fails;

Problem Exploration

I found the problem and started to solve it. I found that service xxx start could not start multiple instances of mysql, but mysqld_multi start could be used; then after various attempts, I found that the mysql environment variables set by /etc/profile could be printed out in a normal environment, but The mysql environment variable cannot be printed in the service made by the shell;

My /etc/frofile file:

export PATH=/usr/local/mysql/bin:$PATH

Execution: You can see that the mysql environment variable is set

[root@localhost init.d]# echo $PATH
/usr/local/mysql/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin

Then we define a system V script

[root@localhost init.d]# vi /etc/init.d/mysqlmul
#!/bin/bash

#chkconfig: - 75 15
#description: test

Give permissions and set it to service

[root@localhost init.d]#chmod +x /etc/init.d/mysqlmul
[root@localhost init.d]#chkconfig --add mysqlmul

Execute service: As a result, you can see that there is no mysql environment variable

[root@localhost init.d]# service mysqlmul start
/sbin:/usr/sbin:/bin:/usr/bin

Solution

1. Add export PATH=/usr/local/mysql/bin:$PATH

## to the service just set in /etc/init.d/xxx #Note:

When putting a shell script into the service, you need to set the PATH and other environments.

Use of environment variable files in service files

Test preparation

c Test program

The contents of LogTest.cpp are as follows:

// 测试代码

#include <stdio.h>
#include <iostream>

using namespace std;

int main(int argc, const char* argv[])
{
    int size = 0;
    // 解析传入参数（argc和argv），代码略
    // ...
    
	cout << size <<endl;
    
	while(1);
	return 0;
}

service file

LogTest.service file

[Unit]
Description=LogTest
After=network.target 

[Service]
Type=simple
EnvironmentFile=-/etc/sysconfig/LogTest
ExecStart=/usr/local/MyTest/LogTest -s ${TESTSIZE}
ExecStop=/bin/kill -s QUIT $MAINPID
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=LogTest

[Install]
WantedBy=multi-user.target

Environment variable file

Environment variable file LogTest is placed in /etc/sysconfig /Under contents.

# 环境变量文件,可根据需要新增
TESTSIZE=10

Test process

1) Compile the c test program and copy the test program to the /usr/local/MyTest/ directory.

cp LogTest /usr/local/MyTest/

2) Log configuration

For log related configuration, please view https://blog. csdn.net/www_dong/article/details/128053496.

3) Service file loading

# 文件拷贝
cp LogTest.service /usr/lib/systemd/system

# 文件加载
systemctl daemon-reload

# 程序启动
systemctl start LogTest

# 查看进程是否启动成功
ps -aux | grep LogTest

4) View LogTest program log

# 进入日志所在目录
cd /var/log

# 查看LogTest.log
cat LogTest.log

Description: The log prints out 10, indicating that the entire process is successful

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