＜高级Bash脚本编程指南＞遇到的一例子的问题

chai21cn

第11章，第1个例子
代码如下

1. #!/bin/bash
   
2. # spawn.sh
   
3. 
   
4. 
   
5. PIDS=$(pidof sh $0)  # Process IDs of the various instances of this script.
   
6. P_array=( $PIDS )    # Put them in an array (why?).
   
7. echo $PIDS           # Show process IDs of parent and child processes.
   
8. let "instances = ${#P_array[*]} - 1"  # Count elements, less 1.
   
9.                                       # Why subtract 1?
   
10. echo "$instances instance(s) of this script running."
    
11. echo "[Hit Ctl-C to exit.]"; echo
    
12. 
    
13. 
    
14. sleep 1              # Wait.
    
15. sh $0                # Play it again, Sam.
    
16. 
    
17. exit 0               # Not necessary; script will never get to here.
    
18.                      # Why not?
    
19. 
    
20. #  After exiting with a Ctl-C,
    
21. #+ do all the spawned instances of the script die?
    
22. #  If so, why?
    
23. 
    
24. # Note:
    
25. # ----
    
26. # Be careful not to run this script too long.
    
27. # It will eventually eat up too many system resources.
    
28. 
    
29. #  Is having a script spawn multiple instances of itself
    
30. #+ an advisable scripting technique.
    
31. #  Why or why not?

复制代码

问题：
按这个例子的意思是不按Ctl-C这个脚本是不会停止的

我运行出错：

6713 6701 6476 5561
3 instance(s) of this script running.
[Hit Ctl-C to exit.]

./spawn.sh: 6: Syntax error: "(" unexpected

lastart

在我的机器上正常.
1690 1582
1 instance(s) of this script running.
[Hit Ctl-C to exit.]

3676 1690 1582
2 instance(s) of this script running.
[Hit Ctl-C to exit.]

3679 3676 1690 1582
3 instance(s) of this script running.
[Hit Ctl-C to exit.]

3682 3679 3676 1690 1582
4 instance(s) of this script running.
[Hit Ctl-C to exit.]

3685 3682 3679 3676 1690 1582
5 instance(s) of this script running.
[Hit Ctl-C to exit.]

3688 3685 3682 3679 3676 1690 1582
6 instance(s) of this script running.
[Hit Ctl-C to exit.]

3691 3688 3685 3682 3679 3676 1690 1582
7 instance(s) of this script running.
[Hit Ctl-C to exit.]