Bash-scriptingHow-ToBeginner · 3 min read

How to Export Variable in Bash: Simple Guide

In bash, you export a variable using the export command, like export VAR=value. This makes the variable available to any child processes started from the current shell.

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Syntax

The basic syntax to export a variable in bash is:

export VARIABLE_NAME=value: Sets and exports the variable in one step.
export VARIABLE_NAME: Exports an already set variable.

Exporting a variable means it will be passed to child processes.

bash

export VARIABLE_NAME=value
# or
VARIABLE_NAME=value
export VARIABLE_NAME

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Example

This example shows how to export a variable and access it in a child process (a subshell).

bash

export MY_VAR="Hello World"
echo "Parent shell: $MY_VAR"
bash -c 'echo "Child shell: $MY_VAR"'

Output

Parent shell: Hello World Child shell: Hello World

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Common Pitfalls

One common mistake is setting a variable without exporting it, so child processes cannot see it.

Wrong way:

MY_VAR="Hello"
bash -c 'echo "$MY_VAR"'  # Outputs nothing

Right way:

export MY_VAR="Hello"
bash -c 'echo "$MY_VAR"'  # Outputs Hello

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Quick Reference

Command	Description
export VAR=value	Set and export variable in one step
VAR=value; export VAR	Set variable then export it
export VAR	Export an existing variable
unset VAR	Remove variable from environment

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Key Takeaways

Use export VAR=value to set and export a variable in one command.

Exported variables are available to child processes started from the shell.

Setting a variable without export keeps it local to the current shell only.

You can export an existing variable by running export VAR.

Use unset VAR to remove a variable from the environment.