How do I export a variable in Linux?

Use 'export VARIABLE=value' to set and export a variable, or 'export VARIABLE' to export an existing shell variable.

How do I see all exported variables?

Run 'export' without arguments to display all exported environment variables, or use 'export -p' for a more detailed format.

export Command

Q: What does the export command do?

The export command sets environment variables and makes them available to child processes. It converts shell variables into environment variables.

The export command sets environment variables and makes them available to child processes. It converts shell variables into environment variables that can be inherited by subprocesses.

Syntax

export [OPTION] [NAME[=VALUE]]...

Description

The export command is a shell builtin that marks variables for automatic export to the environment of subsequently executed commands. It's essential for making variables available to child processes.

Key features:

Convert shell variables to environment variables
Make variables available to child processes
Display all exported variables
Set and export variables in one command
Essential for shell scripting and configuration

Common Options

Option	Description
`-p`	Display all exported variables in a format that can be reused
`-n`	Remove the export property from variables
`-f`	Export functions instead of variables

Examples

Export a new variable

export MY_VAR="Hello World"

Creates and exports a new environment variable

Export existing shell variable

                        MY_VAR="Hello World"
                        export MY_VAR
                    

Exports an existing shell variable to the environment

Display all exported variables

export

Shows all currently exported environment variables

Display in reusable format

export -p

Shows exported variables in a format that can be sourced

Export PATH variable

export PATH="/usr/local/bin:$PATH"

Adds a directory to the PATH environment variable

Export multiple variables

export VAR1="value1" VAR2="value2" VAR3="value3"

Exports multiple variables in one command

Remove export property

export -n MY_VAR

Removes the export property from a variable (keeps it as shell variable)

Export with command substitution

export CURRENT_DATE=$(date)

Exports a variable with the result of command substitution

Export for current session

                        export EDITOR=vim
                        export BROWSER=firefox
                    

Sets common environment variables for the current session

Export function

                        my_function() { echo "Hello from function"; }
                        export -f my_function
                    

Exports a shell function to child processes

Common Use Cases

Setting development environment

                        export JAVA_HOME=/usr/lib/jvm/java-11-openjdk
                        export MAVEN_HOME=/opt/maven
                        export PATH=$JAVA_HOME/bin:$MAVEN_HOME/bin:$PATH
                    

Common setup for Java development environment

Database configuration

                        export DB_HOST=localhost
                        export DB_PORT=5432
                        export DB_NAME=myapp
                        export DB_USER=appuser
                    

Setting database connection parameters

Application configuration

                        export NODE_ENV=production
                        export PORT=3000
                        export DEBUG=false
                    

Common application environment variables