测试 systemd 单元是否在 bash 脚本中处于活动状态
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Test if a systemd unit is active in a bash script
提问by math
I'm writing a script to automatically install a bind server on a CentOs 7 distribution.
我正在编写一个脚本来在 CentOs 7 发行版上自动安装绑定服务器。
I'm stuck with systemctl status, because it does not produce an error code (it's right, since a status is not an error) I can use.
我坚持使用systemctl status，因为它不会产生我可以使用的错误代码（这是正确的，因为状态不是错误）。
What I want is to check whether the service is started (active). What is the best and efficient way to do this?
我想要的是检查服务是否已启动（活动）。做到这一点的最佳和有效方法是什么？
回答by larsks
The best way to check if a service is active is with the systemctl is-activecommand:
检查服务是否处于活动状态的最佳方法是使用以下systemctl is-active命令：
# systemctl start sshd
# systemctl is-active sshd >/dev/null 2>&1 && echo YES || echo NO
YES
# systemctl stop sshd
# systemctl is-active sshd >/dev/null 2>&1 && echo YES || echo NO
NO
回答by voliveira89
If you want to check in a shell script, you can do:
如果要签入 shell 脚本，可以执行以下操作：
if (systemctl -q is-active some_application.service)
then
echo "Application is still running."
exit 1
fi
To check if a application is not running just add a exclamation mark in the condition.
要检查应用程序是否未运行，只需在条件中添加感叹号即可。
