export command

export - Set export attribute for shell variables.

The export command in Linux is a shell built-in used to set environment variables and make them available to child processes (like scripts or new terminal sessions). Environment variables store information (e.g., paths, settings) that programs can access.

Usage: export [-fn] [name[=value] ...]

• name: The variable name to set or export.
• value: The value assigned to the variable (optional).
• No standalone executable; it’s built into shells like bash.

Examples

• Basic Usage

  Set a variable and export it to make it available to subprocesses.

  export MYVAR="Hello"
  • Sets MYVAR to "Hello" and exports it.
  • Child processes (e.g., scripts) can now access MYVAR.

  Verify:

  echo $MYVAR
  • Output: Hello

• Checking Exported Variables

  Use export without arguments to list all exported variables.

  export
  • Output: A list like declare -x MYVAR="Hello", showing all exported variables and their values.

  Alternative:

  printenv
  • Lists only environment variables (similar to export output).

• Exporting an Existing Variable

  If a variable is already set, export makes it available to child processes.

  NAME="Alice"
  echo $NAME  # Works in current shell
  bash -c 'echo $NAME'  # Empty, not exported yet
  export NAME
  bash -c 'echo $NAME'  # Now outputs "Alice"
  Typing `export NAME`Alice
  • Before export, NAME isn’t available in the subprocess (bash -c).
  • After export, it’s accessible.

• Temporary Export

  Variables exported in a session last only until the terminal closes.

  export TEMP="Temporary"
  • TEMP is available until you exit the shell.
  • To make it permanent, add it to a file like ~/.bashrc (see below).

• Permanent Export

  Add export commands to shell configuration files (e.g., ~/.bashrc or ~/.bash_profile) for persistence.

  Edit ~/.bashrc:

  echo 'export MY_PATH="/usr/local/bin"' >> ~/.bashrc
  source ~/.bashrc
  • MY_PATH is now set every time you start a new shell.

• Using with Paths

  Commonly used to modify the PATH variable for executable locations.

  export PATH="$PATH:/home/user/scripts"
  • Adds /home/user/scripts to the search path for commands.
  • Verify: echo $PATH.

To get help related to the export command use --help option

$ export --help
export: export [-fn] [name[=value] ...] or export -p
    Set export attribute for shell variables.

    Marks each NAME for automatic export to the environment of subsequently
    executed commands.  If VALUE is supplied, assign VALUE before exporting.

    Options:
      -f        refer to shell functions
      -n        remove the export property from each NAME
      -p        display a list of all exported variables and functions

    An argument of `--' disables further option processing.

    Exit Status:
    Returns success unless an invalid option is given or NAME is invalid.