shell Concurrence并发

 

1. #!/bin/bash
   
   echo $BASHPID
   
   for _ in `seq 100`;do
           echo start
           sleep 5
           echo $BASH_SUBSHELL
           echo stop
   done &
   
   sleep 20
   

   

    

    7267是脚本进程,其又开启了两个进程7268 7269,7268是for loop放到后台产生的进程与父进程同名
   20S后7267 主脚本进程结束,7269 sleep 20进程结束,7268进程挂靠到systemd下
   

    

    此种情况没有把最主要的循环至于后台并发处理

   #!/bin/bash
   
   echo $BASH_SUBSHELL
   echo $BASHPID
   echo `basename $0`
   
   while true;do
           sleep 5
           echo ppppp
   done &
   
   sleep 10

    

2. #!/bin/bash
   
   echo $BASHPID
   
   for _ in `seq 100`;do
   {
           echo start
           sleep 5
           echo $BASH_SUBSHELL
           echo stop
   } &
   done
   
   sleep 20

   上面的格式把循环并发处理

3. #!/bin/env sh
   
   for b in `seq 1 5`;do
   {
           for p in {a..d};do
                   echo $p
                   sleep 2
           done
   } &
   done
   wait

   上面的脚本实现了5任务并发