What does linux path mean?

In Linux, PATH refers to the environment variable, which generally refers to some parameters in the operating system that specify the operating environment of the operating system; use the command "echo $PATH" to view the current environment variables. If you need to modify it, you can Will be added later. The file under the path configured by path can be executed at any location, and the location of the file can be found through the "which executable file" command.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

linux path environment variable

PATH refers to the environment variable. Use the command echo $PATH to view the current environment. Variables can be appended later if modifications are needed. For example, if you want to add /etc/apache2/bin as an environment variable, you can write:

PATH=$PATH;
/etc/apache2/bin

and then press Enter.

The meaning of environment variables

Environment variables generally refer to some parameters in the operating system that specify the operating environment of the operating system. It is equivalent to a pointer. If you want to view the value of a variable, you need to add "$".

Classification of environment variables

• Divided according to the scope of effect

  Variables in Linux can be divided into environment variables And local variables:

  1) Environment variables: equivalent to global variables, exist in all Shells, and have inheritance;

  2) Local variables: equivalent to local variables only exist in the current Shell , local variables include environment variables, and non-environment variables do not have inheritance.

• According to the life cycle

  1) Permanent: The configuration file needs to be modified, the variable takes effect permanently;

  2) Temporary: Use export definition, close Invalid after Shell.

The role of PATH

To put it simply, PATH is a string variable. When a command is entered, LINUX will search for the path recorded in PATH.

So, the file under the path configured by path can be executed at any location, and the location of the file can be found through which executable file command

View PATH

echo $PATH

Use the env command to display all environment variables: $ env

Use the set command to display all locally defined Shell variables: $ set

Use the unset command to clear environment variables

set can set the value of an environment variable. To clear the value of an environment variable, use the unset command. If no value is specified, the variable value will be set to NULL. An example is as follows:

$ export TEST="Test..." #增加一个环境变量TEST
$ env|grep TEST #此命令有输入，证明环境变量TEST已经存在了
TEST=Test...
$ unset $TEST #删除环境变量TEST
$ env|grep TEST #此命令没有输出，证明环境变量TEST已经存在了

Modify PATH

To add mongodb server as a column

Modification method one:

export PATH=/usr/local/mongodb/bin:$PATH
 //配置完后可以通过echo $PATH查看配置结果。

Effectiveness method: effective immediately

Validity period: temporary change, only valid in the current terminal window, the original path configuration will be restored after the current window is closed

User limitations: only for the current user

Modification method two:

By modifying the .bashrc file:

vim ~/.bashrc 
//在最后一行添上：
export PATH=/usr/local/mongodb/bin:$PATH

Effective method: ( There are the following two types)

• 1. Close the current terminal window and reopen a new terminal window to take effect

• 2. Enter “source ~/.bashrc" command, effective immediately

Validity period: permanently valid

User limitations: only for the current user

Modification method Three:

By modifying the profile file:

vim /etc/profile
 /export PATH //找到设置PATH的行，添加
 export PATH=/usr/local/mongodb/bin:$PATH

Effective method:

• 1. System restart

• 2. If you want it to take effect immediately, you must run # source /etc/profile. Otherwise, it will only take effect the next time you log in as this user.

Validity period: valid forever

User limitations: for all users

Modification method four:

By modifying the environment file:

vim /etc/environment
在PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games"中加入“:/usr/local/mongodb/bin”

Effectiveness method: system restart

Validity period: permanently valid

User limitations: for all users

Commonly used environment variables

PATH determines which directories the shell will search for commands or programs

HOME current user home directory

HISTSIZE Number of historical records

LOGNAME Login name of the current user

HOSTNAME Refers to the name of the host

SHELL Current user Shell type

LANGUGE Language-related environment variables, This environment variable can be modified in multiple languages ​​

MAIL The mail storage directory of the current user

PS1 The basic prompt is # for root users and $

for ordinary users. Related recommendations ：《Linux video tutorial》

The above is the detailed content of What does linux path mean?. For more information, please follow other related articles on the PHP Chinese website!