本文介绍了快速和肮脏的方式,以确保shell脚本只有一个实例同时运行的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
什么是快速和肮脏的方式,以确保只有一个shell脚本的实例在指定时间运行?
What's a quick-and-dirty way to make sure that only one instance of a shell script is running at a given time?
推荐答案
下面是一个使用的锁文件的呼应和一个PID到它的实现。这作为保护,如果进程被杀死后再取出了的 pidfile进程文件的:
Here's an implementation that uses a lockfile and echoes a PID into it. This serves as a protection if the process is killed before removing the pidfile:
LOCKFILE=/tmp/lock.txt
if [ -e ${LOCKFILE} ] && kill -0 `cat ${LOCKFILE}`; then
echo "already running"
exit
fi
# make sure the lockfile is removed when we exit and then claim it
trap "rm -f ${LOCKFILE}; exit" INT TERM EXIT
echo $$ > ${LOCKFILE}
# do stuff
sleep 1000
rm -f ${LOCKFILE}
这里的窍门是杀-0
不提供任何信号,只是检查,如果给定PID的过程中存在。还调用陷阱
将确保的锁文件的当你的进程被终止(除甚至删除杀死-9
)。
The trick here is the kill -0
which doesn't deliver any signal but just checks if a process with the given PID exists. Also the call to trap
will ensure that the lockfile is removed even when your process is killed (except kill -9
).
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