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This article to share with you is about linux environment variable mismatch solution, Xiaobian think quite practical, so share to everyone to learn, I hope you can read this article after some harvest, not much to say, follow Xiaobian to see it.

Friends in linux configuration environment variables when typing the wrong command, resulting in the newly added environment variables overwrite the original environment variables, the direct result is that most of the commands under Linux can not be used, this can scare my friend, he has never encountered such a problem, after my help and explanation, he found that this problem is not terrible, now has been solved, write a blog post, hope to make the same mistakes people quickly solve this problem.

In Linux, divided by the life cycle of variables, Linux variables can be divided into two categories, and their modification methods are as follows:

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

Common profiles include:

(1-1)/etc/profile: effective for all users; this file sets the environment information for each user of the system, when the user is

This file is executed on a login; shell settings are collected from configuration files in the/etc/profile.d directory

For example: edit/etc/profile file, add CLASSPATH variable

# vi /etc/profile

Add a line:

export CLASSPATH=./ JAVA_HOME/lib;$JAVA_HOME/jre/lib

After modification, you need to log in again to take effect, or you can execute the command source /etc/profile to take effect.

(1-2)/etc/bashrc: Effective for all users; execute this file for each user running bash shell. When bash

When the shell is opened, the file is read.

The editing method is as above and will not be repeated.

(1-3)~/.bash_profile: Valid only for the current user; each user can use this file to enter inputs specific to themselves

shell information used, which is executed only once when the user logs in

For example: edit.bash_profile under guok user directory (/home/guok)

$ vi /home/guok/.bash_profile

Add the following:

export CLASSPATH=./ JAVA_HOME/lib;$JAVA_HOME/jre/lib

After modification, you need to log in again to take effect, or you can execute the command source /etc/profile to take effect.

(1-4)~/.bashrc: valid only for the current user; this file contains bash information specific to your bash shell, when

This file is read at login and every time a new shell is opened.

The editing method is the same as above, and will not be repeated again.

In addition, variables (local) set in ~/.bashrc can only inherit variables in/etc/profile, they are "parent-child"

Relationship.

Summary, modify the above file, add the variables you need, when starting a shell (terminal), you

The variables defined will take effect.

(2) Temporary: Use the export command declaration, variables are only available under the current shell(BASH) or its subshell (BASH)

Effective, invalid after closing the shell, and then open a new shell without this variable, if you need to use it, you need to redefine.

Definition method: directly use [export variable name = variable value] under the command line of shell to define variables

Problem phenomena:

Solution:

Direct workaround: Enter export PATH=/usr/bin:/usr/sbin:/bin:/sbin:/usr/X11R6/bin on the command line

After this sentence is executed, it only takes effect temporarily. You need to save this sentence to/etc/profile to take effect permanently.

#source /etc/profile

At this point all environment variables are restored and can be viewed via echo $PATH.

The above is the solution to the mismatch of environmental variables under Linux. Xiaobian believes that some knowledge points may be seen or used in our daily work. I hope you can learn more from this article. For more details, please follow the industry information channel.

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