linux中Shell并发编程示例

Shell是系统的用户界面,提供了用户与内核进行交互操作的一种接口,它接收用户输入的命令并把它送入内核去执行了,下文就来介绍linux中Shell并发编程示例,希望能帮助到各位.

在Python中,有很多模块都可以实现并发编程,比如 threading,processing,eventlet 与 Stackless Python 等.

那么对于Shell而言,又如何实现呢?其实原理很简单,我采用的方法是.

1.将需要执行的任务分批放入后台执行；

2.将后台执行的命令结果汇总到指定的文件中;

3.使用wait命令来等待所有任务执行结束。

下面的脚本就用到了这样的并发编程方法,实现的功能是,快速(3-4秒内)对相同C网内的所有IP(255个)通过命令ping进行测试并返回结果,代码如下:

1. vimfastping.sh
2. #!/bin/bash
3. #defaultsettings
4. subnet=$1#Ctypesubnet
5. retry=2#retrytimes
6. timeout=3#timeoutseconds
7. output=/tmp/ping.output#outputfile
8. #functionprint_help
9. functionprint_help(){
10. echo"Examples:"
11. echo${0}172.17.32
12. echo${0}192.168.1unable
13. exit1
14. }
15. #checktheparameter
16. if[$#-lt1];then
17. print_help
18. fi
19. #checkthenetworkparameter'sformat
20. count=0
21. foriin$(echo$1|sed's/＼.//g')
22. do
23. count=$((${count}+1))
24. done
25. if[${count}-ne3];then
26. print_help
27. fi
28. #cleantheoutputfile
29. >${output}
30. functionpingable(){
31. ping-c${retry}-w${timeout}-q${subnet}.${i}&>/dev/null&&echo${i}>>${output}
32. }
33. functionunpingable(){
34. ping-c${retry}-w${timeout}-q${subnet}.${i}&>/dev/null||echo${i}>>${output}
35. }
36. #getthechecktype
37. if["$2"=="unable"];then
38. status="unpingable"
39. else
40. status="pingable"
41. fi
42. #pingasparallermodeandwriteoutputintofile
43. foriin{1..255}
44. do
45. ${status}&
46. done
47. #waitforallpingprocessesdone
48. wait
49. #printoutputwithbetterorder
50. sum=$(wc-l${output}|awk'{print$1}')
51. echo"Thereare＼"${sum}＼"＼"${status}＼"IPsbeginwith＼"${subnet}.＼":"
52. cat${output}|sort-t"."-k1,1n-k2,2n-k3,3n-k4,4n|xargs-n20echo""
53. chmod+xfastping.sh
54. ./fastping.sh
55. Examples:
56. ./fastping172.17.32
57. ./fastping192.168.1unable
58. time./fastping.sh192.168.1
59. Thereare"142""pingable"IPsbeginwith"192.168.1":
60. 110121314151618192021222324252627282930
61. 3132333435363738404142434445464748495051
62. 5253545556575960616263646566676869707172
63. 7374757677788081838485868788899091929394
64. 9596979899100101102103104105106107108112113114115116117//phpfensi.com
65. 118119120121122123124125126127128133134135136137138139140141
66. 142143149150151152153154155156157158159160161162163164165166
67. 170254
68. real0m3.201s
69. user0m0.135s
70. sys0m0.495s