How to Set and Unset Local, User and System Wide Environment Variables in Linux

Environment Variables are some special variables that are defined in shell and are needed by programs while execution. They can be system defined or user defined. System defined variables are those which are set by system and are used by system level programs.

Set and Unset Linux Environment Variables

For e.g. PWD command is a very common system variable which is used to store the present working directory. User defined variables are typically set by user, either temporarily for the current shell or permanently. The whole concept of setting and un-setting environment variables revolves around some set of files and few commands and different shells.

In Broader terms, an environment variable can be in three types:

1. Local Environment Variable

One defined for the current session. These environment variables last only till the current session, be it remote login session, or local terminal session. These variables are not specified in any configuration files and are created, and removed by using a special set of commands.

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