如何使用bash锁定文件 [英] How to make file lock with bash

问题描述

我有一个任务要从远程服务器中同步目录

I have a task to rsync a dir from remote server

rsync -av [e-mail]:/srv/data/ /srv/data/ 

为使其正常运行并避免脚本"reEnter"问题，我使用rsync progress的pid创建了文件锁"in_progress"，它指示程序是否仍在运行.

To make it run regularly and avoid Script "reEnter" issue, I create a file lock "in_progress" with rsync progress's pid, which indicate whether the program is still running.

lock(){
    echo $1 > in_progress
}

使用此功能来判断rsync进度是否仍在运行:

Using this function to judge whether the rsync progress is still running:

is_running(){
   pid=$(cat in_progress)
   return ps aux | awk '{print $2}' | grep $pid
}

我可以通过此方法获得传递给函数lock的pid

I can get the pid to pass to function lock with this

$!

我必须放置rsync进度背景来获取rsync的pid，所以我明白了

I had to put the rsync progress background to get the pid of rsync, so I get this

rsync -av [e-mail]:/srv/data/ /srv/data/ & 
lock $!

但是当rsync进度完成时，我应该rm锁定文件
我尝试过了

but when rsync progress is done, I should rm the lock file
I tried this

rsync -av [e-mail]:/srv/data/ /srv/data/ && rmLock & 
lock $!

...然后看来我获得的pid不是rsync进度的pid:-(

... then it seems the pid I got is not the pid of rsync progress :-(

推荐答案

如果要防止同时执行，flock是一个不错的工具:

If you want to prevent simultaneous executions , flock is a nice tool:

$ flock -n /path/to/lock/file -c "rsync -av [e-mail]:/srv/data/ /srv/data/" &

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