【RHCE学习笔记1】linux任务的前台和后台执行

jobs 可以查看后台正在运行的作业。

Ctrl+C 可以立即终止正在运行的任务。

Ctrl+Z 可立即将正在运行的任务转到后台暂时挂起并保留在内存中。

fg 【jodid】 回到之前挂起的任务，也可以回到之前使用&符号在后台运行的任务。

简单举例：

[root@TSMClt ~]# whoami

root

[root@TSMClt ~]# jobs

[root@TSMClt ~]#

[root@TSMClt ~]# top

top - 05:08:56 up 1 day, 3:13, 3 users, load average: 0.00, 0.00, 0.00

Tasks: 153 total, 1 running, 152 sleeping, 0 stopped, 0 zombie

Cpu(s): 0.1%us, 0.1%sy, 0.0%ni, 97.5%id, 1.8%wa, 0.0%hi, 0.5%si, 0.0%st

Mem: 996752k total, 822016k used, 174736k free, 33588k buffers

Swap: 1998840k total, 333864k used, 1664976k free, 190192k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

1 root 20 0 19244 1180 964 S 0.0 0.1 0:00.58 init

2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd

3 root RT 0 0 0 0 S 0.0 0.0 0:00.40 migration/0

4 root 20 0 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/0

5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/0

6 root RT 0 0 0 0 S 0.0 0.0 0:00.17 migration/1

7 root 20 0 0 0 0 S 0.0 0.0 0:00.11 ksoftirqd/1

8 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/1

9 root 20 0 0 0 0 S 0.0 0.0 0:00.55 events/0

10 root 20 0 0 0 0 S 0.0 0.0 0:01.16 events/1

11 root 20 0 0 0 0 S 0.0 0.0 0:00.00 cpuset

12 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khelper

13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 netns

14 root 20 0 0 0 0 S 0.0 0.0 0:00.00 async/mgr

15 root 20 0 0 0 0 S 0.0 0.0 0:00.00 pm

16 root 20 0 0 0 0 S 0.0 0.0 0:00.03 sync_supers

17 root 20 0 0 0 0 S 0.0 0.0 0:00.02 bdi-default

18 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kintegrityd/0

19 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kintegrityd/1

20 root 20 0 0 0 0 S 0.0 0.0 0:00.13 kblockd/0

21 root 20 0 0 0 0 S 0.0 0.0 0:01.26 kblockd/1

22 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kacpid

23 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kacpi_notify

24 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kacpi_hotplug

25 root 20 0 0 0 0 S 0.0 0.0 0:00.33 ata/0

26 root 20 0 0 0 0 S 0.0 0.0 0:00.04 ata/1

27 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ata_aux

28 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksuspend_usbd

29 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khubd

30 root 20 0 0 0 0 S 0.0 0.0 0:00.01 kseriod

33 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khungtaskd

34 root 20 0 0 0 0 S 0.0 0.0 0:02.16 kswapd0

[1]+ Stopped top

[root@TSMClt ~]#

使用Ctrl+Z，使得任务到后台挂起。

[root@TSMClt ~]#

[root@TSMClt ~]# jobs

[1]+ Stopped top

[root@TSMClt ~]#

[root@TSMClt ~]# jobs

[1]+ Stopped top

[root@TSMClt ~]# vmstat 1 500

procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----

r b swpd free buff cache si so bi bo in cs us sy id wa st

0 0 333856 173124 33604 190204 1 3 17 24 129 97 0 1 98 2 0

0 0 333856 173124 33604 190204 0 0 0 0 2013 126 0 0 100 0 0

0 0 333856 173124 33604 190204 0 0 0 0 2005 117 0 0 100 0 0

^Z

使用Ctrl+Z，使得任务到后台挂起。

[2]+ Stopped vmstat 1 500

[root@TSMClt ~]# jobs

[1]- Stopped top

[2]+ Stopped vmstat 1 500

[root@TSMClt ~]#

[root@TSMClt ~]#

[root@TSMClt ~]# top &

[3] 8207

[root@TSMClt ~]#

[3]+ Stopped top

[root@TSMClt ~]# jobs

[1] Stopped top

[2]- Stopped vmstat 1 500

[3]+ Stopped top

使用fg命令可以回到之前暂挂的任务。

[root@TSMClt ~]# fg 1

top

top - 05:19:02 up 1 day, 3:23, 3 users, load average: 0.00, 0.00, 0.00

Tasks: 154 total, 1 running, 151 sleeping, 2 stopped, 0 zombie

Cpu(s): 0.0%us, 0.2%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st

Mem: 996752k total, 823760k used, 172992k free, 33604k buffers

Swap: 1998840k total, 333856k used, 1664984k free, 190204k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

8185 root 20 0 14940 1228 912 R 0.3 0.1 0:00.01 top

1 root 20 0 19244 1180 964 S 0.0 0.1 0:00.58 init

2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd

3 root RT 0 0 0 0 S 0.0 0.0 0:00.40 migration/0

4 root 20 0 0 0 0 S 0.0 0.0 0:00.04 ksoftirqd/0

5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/0

6 root RT 0 0 0 0 S 0.0 0.0 0:00.17 migration/1

7 root 20 0 0 0 0 S 0.0 0.0 0:00.11 ksoftirqd/1

8 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/1

9 root 20 0 0 0 0 S 0.0 0.0 0:00.55 events/0

10 root 20 0 0 0 0 S 0.0 0.0 0:01.16 events/1

11 root 20 0 0 0 0 S 0.0 0.0 0:00.00 cpuset

12 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khelper

13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 netns

14 root 20 0 0 0 0 S 0.0 0.0 0:00.00 async/mgr

15 root 20 0 0 0 0 S 0.0 0.0 0:00.00 pm

16 root 20 0 0 0 0 S 0.0 0.0 0:00.03 sync_supers

17 root 20 0 0 0 0 S 0.0 0.0 0:00.02 bdi-default

18 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kintegrityd/0

19 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kintegrityd/1

20 root 20 0 0 0 0 S 0.0 0.0 0:00.13 kblockd/0

21 root 20 0 0 0 0 S 0.0 0.0 0:01.26 kblockd/1

22 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kacpid

23 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kacpi_notify

24 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kacpi_hotplug

25 root 20 0 0 0 0 S 0.0 0.0 0:00.33 ata/0

26 root 20 0 0 0 0 S 0.0 0.0 0:00.04 ata/1

27 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ata_aux

28 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksuspend_usbd

29 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khubd

30 root 20 0 0 0 0 S 0.0 0.0 0:00.01 kseriod

33 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khungtaskd

例子挺简单，但是挺有用，小记之。

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Author: laven54 (lurou)

Email: laven54@163.com

Blog: http://blog.csdn.net/laven54