问题描述
我有一个使用Python编写的守护程序.运行时,它的PID文件位于/tmp/filename.pid.如果守护程序未运行,则PID文件不存在.
I have a daemon I have written using Python. When it is running, it has a PID file located at /tmp/filename.pid. If the daemon isn't running then PID file doesn't exist.
在Linux上,如何检查以确保PID文件存在,如果不存在,请执行命令将其重新启动?
On Linux, how can I check to ensure that the PID file exists and if not, execute a command to restart it?
命令应该是
python daemon.py restart
必须从特定目录执行.
推荐答案
[ -f /tmp/filename.pid ] || python daemon.py restart
-f
检查给定路径是否存在并且是常规文件(只是-e
检查路径是否存在)
-f
checks if the given path exists and is a regular file (just -e
checks if the path exists)
[]
执行测试,并在成功后返回0
,否则返回1
the []
perform the test and returns 0
on success, 1
otherwise
||
是类似于C的or
,因此,如果左侧的命令失败,请执行右侧的命令.
the ||
is a C-like or
, so if the command on the left fails, execute the command on the right.
最后一条语句说,如果/tmp/filename.pid
不存在,则启动守护程序.
So the final statement says, if /tmp/filename.pid
does NOT exist then start the daemon.
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