Bash Small Summary

Bash's configuration file,

Divide by Range:

Global configuration:

/etc/profile,

/etc/profile.d/*.sh

/etc/bashrc

Personal configuration:

~/.bash_profile

~/.bashrc

by function:

Profile class: Provides configuration for the interactive logon shell

/etc/profile,

/etc/profile.d/*.sh

~/.bash_profile

1, define environment variables, such as Path

2. Run the command or script

BASHRC class: Shell provides configuration for non-interactive logon

/etc/bashrc

~/.bashrc

1, used to provide command aliases

2, defining local variables

Variable: variable name is pointer, point to variable

Type:

Environment variables: The current shell and its child processes

Export Name=value

Declare–x Name=value

Local variables: Current process only

Name = value

Local variables: A snippet of code in the current shell process

Position variable: $1,$2

Special variables: $?

How to define:

Bash built-in variables, without definition, can be called directly. PATH

Custom variables:

Assignment method: Variable name = value

Self-increment: name= "$name dddddd"

Weak type!!! Save as character type by default

Pstree can query the process tree

View environment variables

Env

Printenv

Export

Undo Variable

unset name

Reference variable

$name ${name}

Reference symbol

' Strong reference, variable substitution does not occur

"" Weak reference

"Command reference, the execution result of the reference command

Shell Logon Type:

Interactive: Direct Terminal su-username

Non-interactive: graphical interface su username

Order of action at logon

Interactive:/etc/profile->/etc/profile.d/*.sh-> ~/.bash_profile

The following overrides the previous

Non-interactive:~/.bashrc–>/etc/bashrc–>/etc/profile.d/*.sh

How the new configuration takes effect:

1, re-login

2, reread the configuration file

Source/path/to? Somefile

. /path/to? Somefile

After the experiment, correct:

1. How do I define an alias that is valid for the user you are using?

/ETC/BASHRC I guess it's here to change,

2. What to do if only the modification of the PATH environment variable takes effect for the root user

~/.BASHRC Modify the root of this file

Bash Small Summary