编写脚本，实现同一个脚本多次运行，系统中只有一个进程

root@nfs scripts]#cat pid.sh

#!/bin/shpidpath=/tmp/a.pidif[-f"$pidpath"]thenkill`cat$pidpath`>/dev/null2>&1rm-f$pidpathfiecho$$>$pidpathsleep300

测试如下

root@nfs scripts]# ps -ef|grep pid.sh|grep -v grep

[root@nfs scripts]# sh pid.sh &

[1] 3883

[root@nfs scripts]# ps -ef|grep pid.sh|grep -v grep

root 3883 1297 0 20:36 pts/0 00:00:00 sh pid.sh

[root@nfs scripts]# sh pid.sh &

[2] 3890

[root@nfs scripts]# sh pid.sh &

[3] 3894

[1] Terminated sh pid.sh

[root@nfs scripts]# sh pid.sh &

[4] 3898

[2] Terminated sh pid.sh

[root@nfs scripts]# ps -ef|grep pid.sh|grep -v grep

root 3898 1297 0 20:36 pts/0 00:00:00 sh pid.sh

[3]- Terminated sh pid.sh