The export command in Linux is a fundamental tool for setting environment variables. These variables are dynamic values that influence the behavior of running processes by storing information like executable paths, configuration settings, and other data accessible to programs.

The command syntax is export VARNAME=value, where VARNAME represents the variable’s name and value is its assigned value. Once exported, a variable becomes available to all child processes of the current shell.

export is commonly used in shell scripts and configuration files to define system or application-specific environment variables. It can also be used interactively on the command line for temporary variable assignments.

The export command is a built-in shell feature, eliminating the need for separate installation across major Linux distributions like Ubuntu, CentOS, and Fedora.

Installation

No installation is required as export is an inherent part of the Linux shell.

Usage

Here are usage examples demonstrating how to set environment variables using the export command:

Example 1: Setting a Single Environment Variable

Syntax:

export VARNAME=value

Example: Adding a new directory to the PATH variable:

export PATH=$PATH:/path/to/new/directory

This command extends the existing PATH by appending /path/to/new/directory.

Example 2: Setting Multiple Environment Variables

Multiple variables can be set with a single command, separated by spaces:

export VAR1=value1 VAR2=value2 VAR3=value3

This assigns value1, value2, and value3 to VAR1, VAR2, and VAR3, respectively.

Example 3: Exporting Variables for a Specific Command

Temporarily set variables for the duration of a command:

export VARNAME=value command

VARNAME is set to value specifically for the execution of command, reverting to its original value afterward.

Similar Commands

Alternatives for managing environment variables include:

• set: Used to set shell options and positional parameters, and can display current environment variables.
• env: Displays environment variables or executes a command within a modified environment.
• printenv: Prints the values of environment variables.

Script Examples

Following are script examples demonstrating automation using export:

Example 1: Setting Variables Within a Script

This script sets PATH and LD_LIBRARY_PATH and then executes another command.


#!/bin/bash
export PATH=$PATH:/path/to/new/directory
export LD_LIBRARY_PATH=/path/to/library
command


Example 2: Using Environment Variables in a Script

This script utilizes the PATH to locate an executable.


#!/bin/bash
export PATH=$PATH:/path/to/new/directory
executable


Example 3: Exporting Variables for a Specific Command

A script demonstrating variable export for a singular command.


#!/bin/bash
export VARNAME=value command


List of Possible Functions and Constants

Command/Constant	Description
export VARNAME=value	Sets the value of the environment variable VARNAME to value.
set	Sets shell options and positional parameters. Can also display current environment variables.
env	Displays current environment variables or runs a command in a modified environment.
printenv	Displays the values of the current environment variables.

Conclusion

The export command is a valuable tool in Linux for managing environment variables, enabling users to configure and customize the behavior of the operating system and applications.

Environment variables are widely used by system administrators, developers, and power users alike for tasks such as defining application configuration or customizing system behavior. The export command standardizes managing these variables ensuring their accessibility cross processes.

Mastering the export command is essential for anyone working regularly within a Linux environment for effective environment variable management and system behavior customization.

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