Shell Primer-shelltexing

1. About!

Command:!!

Description: Executes the previous command

[Email protected] ~]# pwd
/root
[[email protected] ~]#!!
Pwd
/root

Command:! N (n = number)

Description: Executes the nth command in the command history

Extended command: History

Description: View command history

[Email protected] ~]# history

.......

1058 vim. BASHRC
1059 pwd
1060 History

[Email protected] ~]#!1059
Pwd
/root

Command:! Character

Description:! P For example, executes the last command in the command history that begins with P

[Email protected] ~]#!p
Pwd
/root

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2. About command aliases

Command: Alias "command alias" = "' Specific Command '"

Description: Customize a name to the command, the current shell is valid

Command: Unalias "command alias"

Description: Canceling command aliases

[[email protected] ~]# alias denny= ' pwd '
[Email protected] ~]# Denny
/root

[Email protected] ~]# Unalias Denny
[Email protected] ~]# Denny
-bash:denny:command not found

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3. About redirection

Command:>

Description: Output Redirect, delete the contents of the file, write the new

[email protected] 111]# cat 1.txt
1111
[Email protected] 111]# echo ' 222 ' >1.txt
[email protected] 111]# cat 1.txt
222

Command:>>

Description: Append redirect, write on the original base of the file below

[Email protected] 111]# echo ' 333 ' >>1.txt
[email protected] 111]# cat 1.txt
222
333

Command:<

Description: Enter the redirect to enter the contents of the file to the front

[Email protected] 111]# Wc-l<1.txt
2

Command:2>;2>>

Description: Error redirection, append error redirection. Redirect or append the wrong content to a file

[[email protected] 111]# ls 5 2> 1.txt
[email protected] 111]# cat 1.txt
LS: Unreachable 5: No file or directory

[[email protected] 111]# ls 5 2>> 1.txt
[email protected] 111]# cat 1.txt
LS: Unreachable 5: No file or directory
LS: Unreachable 5: No file or directory

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4. About Pipe breaks

Command: "full command" | "command"

Description: Throw the result from the previous command to the command following the pipe symbol to process

[email protected] 111]# Cat 1.txt | Wc-l
3

[[email protected] 111]# ls
1 11.txt 1.txt
[[email protected] 111]# ls./*.txt | Xargs RM-RF
[[email protected] 111]# ls
1

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5. About wildcard Match characters

Command: *

Description: can represent multiple characters

[[email protected] 111]# ls
1 11.txt 1.txt 22.txt 2.txt 33.txt 3.txt 44.zip 55.zip
[[email protected] 111]# ls *.txt
11.txt 1.txt 22.txt 2.txt 33.txt 3.txt

Command:?

Description: Represents a character

[[email protected] 111]# ls
1 11.txt 1.txt 22.txt 2.txt 33.txt 3.txt 44.zip 55.zip
[email protected] 111]# ls?. Txt
1.txt 2.txt 3.txt

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6. About process pause, view pause, resume, background run, end process

Shortcut key: Ctrl + Z

Description: Process paused

[[email protected] 111]# Sleep 100
^z
[1]+ Stopped Sleep 100

[[email protected] 111]# Sleep 200
^z
[2]+ Stopped Sleep 200

Command: Jobs

Description: View the paused process,

[[email protected] 111]# jobs
[1]-Stopped Sleep 100
[2]+ Stopped Sleep 200

Command: FG;FG "number"

Description: Resume the pause process, followed by a plus sign with a priority recovery,-number second, you can also resume the process in the specified pause

[[email protected] 111]# FG
Sleep 200

^z

[2]+ Stopped Sleep 200

[[email protected] 111]# jobs
[1] Stopped sleep 100
[2]-Stopped Sleep 200
[3]+ Stopped Sleep 300
[[email protected] 111]# FG 2
Sleep 200
^z
[2]+ Stopped Sleep 200

Command: BG;BG "number"

Description: The background runs the pause process, the number followed by the plus sign of the priority background run,-number second, you can also specify a process in the background run pause & indicate background run

[[email protected] 111]# BG 2
[2]-Sleep &
[[email protected] 111]# jobs
[1]-Stopped Sleep 100
[2] Running Sleep &
[3]+ Stopped Sleep 300

Shortcut keys: Ctrl + C

Description: End Process

[[email protected] 111]# FG
Sleep 300
^c

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7. Closed the current shell, how to end the process

Command: PS aux

Description: View Process

[[Email protected] 111]# PS aux |grep sleep
Root 1693 0.0 0.0 100904 596 pts/0 T 21:32 0:00 sleep 100
Root 1697 0.0 0.0 100904 596 pts/0 T 21:36 0:00 sleep 100000
Root 1703 0.0 0.0 103252 880 pts/0 s+ 21:38 0:00 grep sleep

Command: Kill

Option:-9: Mandatory

Description: End Process

[Email protected] 111]# kill-9 1697
[3]+ has killed sleep 100000

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Summarize:!! ！ N//!  *//alias unalias//> >> < 2> 2>>//*? CTRL + Z FG BG Jobs CTRL + C/PS aux kill//

Shell Primer-shelltexing