22.Shell Special symbols and Cut,sort,wc,uniq,tee,tr,split commands

Five Week fifth session (January 12)

8.10 Shell Special Symbol Cut command

8.11 Sort_wc_uniq Command

8.12 tee_tr_split Command

8.13 Shell Special Symbol

Related Quiz title: http://ask.apelearn.com/question/5437

Extended

1. SOURCE Exec Difference http://alsww.blog.51cto.com/2001924/1113112
2. Linux Special symbols Daquan http://ask.apelearn.com/question/7720
3. Sort is not sorted by ASCII http://blog.csdn.net/zenghui08/article/details/7938975

A special symbol

• [] * Any arbitrary character, wildcard characters

• [ ] ? Any one character

• [] # comment characters

• [] \ de-semantic characters

• [ ] | Pipe character

[email protected]:~# a=1[email protected]:~# b=2[email protected]:~# c=$a$b[email protected]:~# echo $c12[email protected]:~# c=\$a\$b[email protected]:~# echo $c$a$b

Two commands related to pipelines

• [] Cut split,-D delimiter-F Specify segment number-C to specify the first word

[email protected]:~# cat /etc/passwd |head -2root:x:0:0:root:/root:/bin/bashbin:x:1:1:bin:/bin:/sbin/nologin[email protected]:~# cat /etc/passwd |head -2 |cut -d ":" -f 1 //只取第一段rootbin[email protected]:~# cat /etc/passwd |head -2 |cut -d ":" -f 1,2 //取第一段，第二段root:xbin:x[email protected]:~# cat /etc/passwd |head -2 |cut -c 4t:

• [] Sort sort,-n with numeric sort-R reversed-T delimiter-kn1/-kn1,n2
  

[email protected]:~# sort -r /etc/passwdxavi:x:1000:1000:xavi,xavi‘s office,62580558,62589906:/home/xavi:/bin/bashxavidsf:x:1001:1001:xavi:/home/xavidsf:/bin/bashusbmuxd:x:113:113:usbmuxd user:/:/sbin/nologinunbound:x:993:991:Unbound DNS resolver:/etc/unbound:/sbin/nologintss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologintest:x:1002:1002::/home/test:/bin/bash

• [] wc-l statistics number of rows-m statistic characters-W statistics

[email protected]:~# vi 2.txt[email protected]:~# cat 2.txt2221dedddededed121332e4ded[email protected]:~# wc -l 2.txt6 2.txt[email protected]:~# wc -m 2.txt32 2.txt[email protected]:~# wc -w 2.txt6 2.txt

• [] Uniq, C count the number of rows, the contents of the file is unchanged

[email protected]:~# sort 2.txt|uniq  //必须先给文件排序，才能生效111121322221dedd3323232e4444deddede

[email protected]:~# sort 2.txt|uniq -c  //统计重复次数，      1 1      1 11      1 1213      2 2      1 2221dedd      2 3      1 3232      1 32e4      1 444      2 ded      1 dede

• [] tee and > Similar, redirection is also displayed on the screen

[email protected]:~# echo "dadsaddsdad" |tee a.txtdadsaddsdad[email protected]:~# sort 2.txt|uniq -c |tee a.txt      1 1      1 11      1 1213      2 2      1 2221dedd      2 3      1 3232      1 32e4      1 444      2 ded      1 dede

• [] te-a and >> similar, chasing aggravated orientation

  [email protected]:~# sort 2.txt|uniq -c |tee -a a.txt  1 1  1 11  1 1213  2 2  1 2221dedd  2 3  1 3232  1 32e4  1 444  2 ded  1 dede[email protected]:~# cat a.txt  1 1  1 11  1 1213  2 2  1 2221dedd  2 3  1 3232  1 32e4  1 444  2 ded  1 dede  1 1  1 11  1 1213  2 2  1 2221dedd  2 3  1 3232  1 32e4  1 444  2 ded  1 dede

• [] TR replacement character, tr ' a ' B ', case replacement TR ' [A-z] ' [A-z] '//[] means any number of characters in parentheses are selected

[[email protected] ~]# echo "xavilinux" |tr ‘[al]‘ ‘[AL]‘xAviLinux[[email protected] ~]# echo "xavilinux" |tr ‘a‘ ‘A‘xAvilinux

• [] Split cut,-B size (default unit byte),-L line number

-B means that the document is split by size in bytes

[[email protected] ~]# mkdir split_dir[[email protected] ~]# cd !$cd split_dir[[email protected] split_dir]# cp /etc/passwd ./[[email protected] split_dir]# split -b 500 passwd[[email protected] split_dir]# lspasswd  xaa  xab  xac  xad  xae

To see the actual size, Du-sh is looking at the block, du-sb the size by byte

If split does not specify a target file name, it will be Xaa, Xab ... Such a filename to access the cut file. Specify the target file name, as follows:

[[email protected] split_dir]# rm -f x* //把前面分割好的文件全部删除[[email protected] split_dir]# split -b 100 passwd 123[[email protected] split_dir]# ls123aa  123ad  123ag  123aj  123am  123ap  123as  123av  passwd123ab  123ae  123ah  123ak  123an  123aq  123at  123aw123ac  123af  123ai  123al  123ao  123ar  123au  123ax

-L to divide the document by the number of rows

[[email protected] split_dir]# rm -f 123*[[email protected] split_dir]# split -l 10 passwd //10行分割[[email protected] split_dir]# wc -l *  46 passwd  10 xaa  10 xab  10 xac  10 xad   6 xae  92 总用量

Special symbols for three shells 1, special symbols $

$ can be used as an identifier in front of a variable, and you can! Used in combination.

[[email protected] /]# touch 1.txt[[email protected] /]# ls 1.txt1.txt[[email protected] /]# ls !$ls 1.txt1.txt

!$ represents the last variable of the previous command, in this case the last command is 1.txt, then entering!$ under the current command means 1.txt

2, special symbols;

To run two or more two commands in a single line of commands, you need to add a symbol between the commands.

[[email protected] /]# ls 1.txt ; wc -l 2.txt1.txt8 2.txt[[email protected] /]# ls 1.txt;wc -l 2.txt //命令之间不空格也是有效的，1.txt8 2.txt

3. Special Symbols ~

The symbol ~ Represents the user's home directory, the root user's home directory is/root, the normal user's home directory is/home/username.

4. Special Symbols &

If you put a command in the background, you need to add the symbolic &, which is usually used for long commands. For example, it can be used after sleep, as shown below:

[[email protected] /]# sleep 30 &[2] 7047[[email protected] /]# jobs[1]+  已停止               wc -l(工作目录：~/split_dir)[2]-  运行中               sleep 30 &

5. REDIRECT Symbols >, >>, 2> and 2>&gt, error and correct input &>

and >> the meaning of substitution and append respectively. When we run a command error, the error message is output to the current screen. If you want to redirect to a text, use the redirect symbol 2> or 2>>, which represent error redirection and error append redirection, respectively.

6. Brackets []

The combination of characters in brackets, representing any of the character combinations, can also represent a range (1-3,a-z).

7. Special Symbols && | |

A semicolon has just been mentioned above for the delimiter between multiple commands. There are also two special symbols that can be used in the middle of multiple commands, that is, "&&" and "| |" are all listed below:

Command1; Command2

Command1 && Command2

Command1 | | Command2

When using ";", Command2 will be executed regardless of whether Command1 is executed successfully;

When using "&&", only if the Command1 is executed successfully, Command2 will execute, otherwise command2 not execute;

When using "| |", the Command1 execution succeeds Command2 not execute, otherwise go to execute Command2, in short Command1 and Command2 always have a command to execute.

[[email protected] /]# ls 1a.txt; wc -l 2.txtls: 无法访问1a.txt: 没有那个文件或目录[2]-  完成                  sleep 308 2.txt[[email protected] /]# ls 1.txt || wc -l 2.txt1.txt[[email protected] /]# ls 1.txt && wc -l 2.txt1.txt8 2.txt[[email protected] /]# ls 1a.txt && wc -l 2.txtls: 无法访问1a.txt: 没有那个文件或目录

22.Shell Special symbols and Cut,sort,wc,uniq,tee,tr,split commands