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This article mainly explains "what is the function of Bash shell under Linux". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "what is the function of Bash shell under Linux".

Know the Shell of BASH

The function of Bash shell

Command editing capability (history):

Just press the up and down keys on the command line to find the first / last input instruction. where are so many instructions recorded? .bash _ history in your home folder.

Command and file completion: (benefits of [tab] button)

Command alias setting function: (alias)

Alias lm='ls-al'

Programmatic script: (shell scripts)

Query whether the instruction is a built-in command for Bash shell: type

Example 1: check whether the ls instruction is built into bash?

Variable function of [dmtsai@study ~] $type lsShell

Variable access and setting: echo, variable setting rules, unset

Echo $PATH

Set the variable:

[dmtsai@study ~] $echo ${myname} >

Standard error output (stderr): code 2, use 2 > or 2 >; to understand stdout and stderr, let's do a sample exercise: example 1: observe the file names, permissions and attributes of each directory under your system root directory (/) and record them

[dmtsai@study] $ll / = at this point the screen will display the file name information [dmtsai@study ~] $ll / > ~ / rootfile = = there is no information on the screen [dmtsai@study ~] $ll ~ / rootfile = = A new file has been created! -rw-rw-r--. 1 dmtsai dmtsai 1078 Jul 9 18:51 / home/dmtsai/rootfile

1 >: output "correct data" to a specified file or device by overwriting method; 1 > >: output "correct data" to a specified file or device by cumulative method; 2 >: output "incorrect data" to a specified file or device by overwriting method; 2 > >: output "incorrect data" to a specified file or device by cumulative method

Example 5: write all the data of the instruction to a file named list

[dmtsai@study ~] $find / home-name .bashrc > list 2 > list = = error [dmtsai@study ~] $find / home-name .bashrc > list 2 > & 1 = correct [dmtsai@study ~] $find / home-name .bashrc & > list = correct

Standard input: < and

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