linux[Basic]-12-Important environment variables [01]

Important Environment variables

There are many environment variables in the Linux system, we can use Env to view his

Variables are made up of fixed "variable names" and user-defined "variable values".

Variable name	Role
HOME	User's home directory "Home"
SHELL	the current shell that's the program .
Histsize	History command record number of bars
MAIL	Mail Box File
Lang	Language data
RANDOM	Random numbers
PS1	Bash prompt
Histfilesize	History number of command stores
PATH	Find the execution file in the current directory
EDITOR	Default text Editor

View the user's home directory by variable:

[Email protected] ~]# echo $HOME

/root

[Email protected] ~]# Su-linuxs

[Email protected] ~]$ echo $HOME

/home/linuxs

Set a variable "Workdir" so that each user executes

"CD $WORKDIR" are logged into the/home/workdir directory.

[Email protected] ~]# mkdir-p/home/workdir

[Email protected] ~]# Workdir=/home/workdir

[Email protected] ~]# CD $WORKDIR

[Email protected] workdir]# pwd

/home/workdir

[Email protected] workdir]# Su-linuxs

Last Login:thu-17:26:01 CST on pts/0

[Email protected] ~]$ CD $WORKDIR

[Email protected] ~]$ echo "$WORKDIR"

[Email protected] ~]$ # because of the scope of the variable

So you can use the Export command to promote local variables to global variables.

Format: Export variable name [= Variable value]

[Email protected] linuxs]# export WOD

[email protected] linuxs]# su Linuxs

[Email protected] ~]$ echo "$WOD"

/home/workdir

[Email protected] ~]$ CD $WOD

[Email protected] workdir]$ pwd

/home/workdir

linux[Basic]-12-Important environment variables [01]