export Command Cheat Sheet

The export command marks variables and functions to be passed to child processes. Without export, a variable defined in a shell is local to that shell and not visible to scripts or commands it runs.

Synopsis

export [-fn] [name[=value] ...]
export -p

Basic Usage

Export a Variable

Define a variable and export it in one step.

export MY_VAR="Hello World"

Export Existing Variable

Define first, export later.

MY_VAR="Hello World"
export MY_VAR

Viewing Exports

List All Exported Variables (-p)

Displays all variables currently exported to child processes.

export -p

Managing Exports

Un-export a Variable (-n)

Removes the "exported" property from a variable. The variable remains set in the current shell but will not be passed to child processes.

export -n MY_VAR

Export Functions (-f)

You can export Bash functions so they are available in subshells and scripts.

my_function() {
  echo "I am available everywhere!"
}

export -f my_function
bash -c 'my_function'

Common Key Variables

Persistence

export only affects the current shell session. To make changes permanent:

For specific user: Add to ~/.bashrc (interactive) or ~/.profile (login).

echo 'export PATH=$PATH:/opt/bin' >> ~/.bashrc
source ~/.bashrc

For all users: Add to /etc/profile or a file in /etc/profile.d/.

Child Process Inheritance

Understanding scope is key.

1. Local Variable (Not Exported)

VAR="local"
bash -c 'echo $VAR'
# Output: (empty)

2. Exported Variable

export VAR="global"
bash -c 'echo $VAR'
# Output: global

3. Child cannot change Parent A child process receives a copy of the environment. Changes do not propagate back up.

export COUNTER=1
bash -c 'export COUNTER=5'
echo $COUNTER
# Output: 1

Examples

Setting PATH

Adding a directory to your command path is the most common use case.

export PATH=$PATH:/home/user/my_scripts

Setting Default Editor

export EDITOR=nano

Scripting with env

While export sets the variable for the current shell and all future children, env sets it for just one command.

# Permanent for session
export DEBUG=1
./script.sh

# Temporary for one command
env DEBUG=1 ./script.sh

Exit Status

Notes

• export is a shell builtin.
• Variable names must start with a letter or underscore, and contain only letters, numbers, and underscores.
• Security: Be careful exporting sensitive data (like API keys) if you are running untrusted scripts, as they can read any exported variable.