"CentOS" Learning Bash

First, the characteristics

Command history,!! ,!$,! character,!n (n is the first few commands)

tab can complete file path or command

Alias a= "B", unalias A, how to see which alias is defined, just hit alias

input and output redirection; >>, <,2>,2>>

Pipe Symbols |

Job Control CTRL + Z, CTRL + C, FG, BG

"Weak parsing, ' strong parsing, ' equivalent to returning ' The result of the command,

* Wildcard,? Wildcard, #注释, $ reference variable, multiple commands are written on one line, & run in the background, && logic and

Second, the variable

Env Current user all environment variables

Set user-owned variables + their own defined variables, unste

Export declared as global variable

echo Display Variable

Third, bash shell configuration file

1. System Setting value

/etc/profile

/etc/bashrc

2. Personal Setting value

~/.BASHRC, open a shell when executing

~/.bash_profile, when the user logs on to execute

~/.bash_history

~/.bash_logout

For the execution order, if the user logs on, the RC is executed before the profile is executed.

Then → figure this out. = = Source, which is the immediate new configuration

Three, Pipeline command

1.cut-d "Split symbol" [-CF] Fields

-D followed by delimiters, default to spaces

-C is followed by the first few characters

The number of blocks is followed by-F.

Eg:cut-d ":"-F 1/ETC/PASSWD

2.sort [-t delimiter] [-NRU]

-N using pure numeric sorting

-R Reverse Sort

-U the same line that appears is listed only once

2.1 Uniq [-c]

Show only one

-C in digital arrangement

3.WC [-LMW] [filename]

-L How many lines

-m number of characters

-W How many words

4.tee

Equivalent to being redirected and displaying content on the screen

5.tr replacement

Eg:ls-al |tr ' A-Z ' A-z change all lowercase to uppercase

6.split [-BL] Split

-B Split according to file size

-L Divide line according to number of lines

Eg:split-l 100/etc/passwd Thenameyouwant

Split-b 1m/etc/passwd Thenameyouwant

Written in the back//////////////////////////////////////////////////////////

I dragged it even more! Drag the more!! Drag the more!!!

It turns out I'm really a bit of a procrastination!!!!

Some feel that their study efficiency is a little low AH recently!!!!!

"CentOS" Learning Bash