LPI学习笔记 -----2

正顺序读一个文件和反顺序读一个文件

1. [root@btg vim_plugin_config]# cat README
2. This tarball is autoconfig vim ,
3. it can install some config file
4. and plugin file in to your vim
5. [root@btg vim_plugin_config]# tac README
6. and plugin file in to your vim
7. it can install some config file
8. This tarball is autoconfig vim ,
9. [root@btg vim_plugin_config]#

读取文件末尾处的内容

tail -n默认读取末尾十行的内容

tail -n 可以指定读末尾指定行数的内容

1. [root@btg ~]# tail a
2. <6>[ 31.625063] [audpp.c:audpp_dsp_event] DISABLE
3. <6>[ 31.626963] [audpp.c:audpp_disable] Received CFG_MSG_DISABLE from ADSP
4. <6>[ 31.626986] [adsp.c:msm_adsp_disable] disable 'AUDPPTASK'
5. <6>[ 31.629338] [adsp.c:msm_adsp_put] closing module AUDPPTASK
6. <6>[ 31.629381] [audmgr.c:audmgr_disable] session 0xc070cfa0
7. <6>[ 31.631244] [audmgr.c:audmgr_rpc_thread] rpc_reply status 0
8. <3>[ 31.640831] [audmgr.c:process_audmgr_callback] DISABLED
9. <6>[ 31.971498] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
10. <6>[ 32.052659] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
11. <6>[ 32.086464] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
13. [root@btg ~]# tail -n 15 a
14. <7>[ 24.038064] BATT: voltage = 4200 mV [capacity = 100%]
15. <6>[ 27.021079] [snd.c:snd_ioctl] snd_set_volume 31 0 6
16. <6>[ 27.479176] [xsensor] als_power_ctl val = 1
17. <6>[ 27.594288] request_suspend_state: wakeup (3->0) at 27593166742 (2011-05-16 10:40:30.217523356 UTC)
18. <4>[ 27.728714] gsensor_enable_store 1
19. <6>[ 31.625063] [audpp.c:audpp_dsp_event] DISABLE
20. <6>[ 31.626963] [audpp.c:audpp_disable] Received CFG_MSG_DISABLE from ADSP
21. <6>[ 31.626986] [adsp.c:msm_adsp_disable] disable 'AUDPPTASK'
22. <6>[ 31.629338] [adsp.c:msm_adsp_put] closing module AUDPPTASK
23. <6>[ 31.629381] [audmgr.c:audmgr_disable] session 0xc070cfa0
24. <6>[ 31.631244] [audmgr.c:audmgr_rpc_thread] rpc_reply status 0
25. <3>[ 31.640831] [audmgr.c:process_audmgr_callback] DISABLED
26. <6>[ 31.971498] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
27. <6>[ 32.052659] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
28. <6>[ 32.086464] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
29. [root@btg ~]# tail -n 1 a
30. <6>[ 32.086464] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
31. [root@btg ~]# tail -f a
32. <6>[ 31.625063] [audpp.c:audpp_dsp_event] DISABLE
33. <6>[ 31.626963] [audpp.c:audpp_disable] Received CFG_MSG_DISABLE from ADSP
34. <6>[ 31.626986] [adsp.c:msm_adsp_disable] disable 'AUDPPTASK'
35. <6>[ 31.629338] [adsp.c:msm_adsp_put] closing module AUDPPTASK
36. <6>[ 31.629381] [audmgr.c:audmgr_disable] session 0xc070cfa0
37. <6>[ 31.631244] [audmgr.c:audmgr_rpc_thread] rpc_reply status 0
38. <3>[ 31.640831] [audmgr.c:process_audmgr_callback] DISABLED
39. <6>[ 31.971498] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
40. <6>[ 32.052659] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
41. <6>[ 32.086464] binder: 70:70 BC_REQUEST_DEATH_NOTIFICATION death notification already set
45. test for tail command
46. ^C
47. [root@btg ~]#

tail -f，读取文件末尾的内容，并且实时获得文件末尾新增加的内容

tr用来作字符转换

1. [root@btg ~]# cat README |tr a-z A-Z
2. THIS TARBALL IS AUTOCONFIG VIM ,
3. IT CAN INSTALL SOME CONFIG FILE
4. AND PLUGIN FILE IN TO YOUR VIM
5. [root@btg ~]# cat README |tr c K
6. This tarball is autoKonfig vim ,
7. it Kan install some Konfig file
8. and plugin file in to your vim
9. [root@btg ~]# cat README |tr \ 0
10. This0tarball0is0autoconfig0vim0,0
11. it0can0install0some0config0file0
12. and0plugin0file0in0to0your0vim
13. [root@btg ~]#

tr删除字符

1. [root@btg ~]# cat README |tr -d c
2. This tarball is autoonfig vim ,
3. it an install some onfig file
4. and plugin file in to your vim
5. [root@btg ~]#
6. [root@btg ~]#
7. [root@btg ~]# cat README |tr -d abc
8. This trll is utoonfig vim ,
9. it n instll some onfig file
10. nd plugin file in to your vim

显示文本内容处理，文本内容排序处理

1. [root@btg ~]# cat testfile
2. aaaaaa
3. bbbbbb
4. cccccc
5. dddddd
6. eeeeee
7. aaaaaa
8. bbbbbb
9. cccccc
10. cccccc
11. dddddd
12. eeeeee
13. aaaaaa
14. [root@btg ~]# uniq -d testfile
15. cccccc
16. [root@btg ~]# uniq -u testfile
17. aaaaaa
18. bbbbbb
19. cccccc
20. dddddd
21. eeeeee
22. aaaaaa
23. bbbbbb
24. dddddd
25. eeeeee
26. aaaaaa
27. [root@btg ~]# sort testfile |uniq
28. aaaaaa
29. bbbbbb
30. cccccc
31. dddddd
32. eeeeee
33. [root@btg ~]# sort testfile |uniq -d
34. aaaaaa
35. bbbbbb
36. cccccc
37. dddddd
38. eeeeee
39. [root@btg ~]#

wc查看文件大小，内容多少

1. [root@btg ~]# wc -l testfile
2. 12 testfile
3. [root@btg ~]# wc -c testfile
4. 84 testfile
5. [root@btg ~]# wc -w testfile
6. 12 testfile
7. [root@btg ~]# cat testfile
8. aaaaaa
9. bbbbbb
10. cccccc
11. dddddd
12. eeeeee
13. aaaaaa
14. bbbbbb
15. cccccc
16. cccccc
17. dddddd
18. eeeeee
19. aaaaaa
20. [root@btg ~]#
21. [root@btg ~]# cat -n testfile
22.      1    aaaaaa
23.      2    bbbbbb
24.      3    cccccc
25.      4    dddddd
26.      5    eeeeee
27.      6    aaaaaa
28.      7    bbbbbb
29.      8    cccccc
30.      9    cccccc
31.     10    dddddd
32.     11    eeeeee
33.     12    aaaaaa
34. [root@btg ~]#