export

Set an environment variable

$ export [VARIABLE]=[value]

$ export PATH=$PATH:[path/to/append]

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

-f
    Treat function names as arguments; export functions instead of variables

-n
    Remove export attribute from variables (make them local)

-p
    Print all exported names and values in a format usable as shell input

name[=word]
    Variable name to export; optional =word sets or overrides its value

The export command is a shell builtin that marks variables (or functions) for export to the environment of child processes. When a variable is exported, its name and value are passed to subsequently executed commands, scripts, or subshells, allowing them to inherit and use these settings.

Without export, variables remain local to the current shell session. Common use cases include setting PATH, HOME, or custom variables like EDITOR.

For instance:
export PATH=/usr/local/bin:$PATH
This prepends /usr/local/bin to the PATH for all child processes.

export can also list all exported variables with -p, remove the export attribute (making it local again) with -n, or handle function names with -f. Multiple variables can be exported at once: export VAR1=value1 VAR2=value2.

Exported values are strings; complex data structures require serialization. Changes do not affect the parent shell, only children. This ensures environment isolation while enabling configuration propagation.

Export affects only child processes, not parent shell. Functions exported with -f are copied by value. Infinite recursion possible if functions reference themselves during export.

export -p | grep PATH — List exported PATH.
export -n DISPLAY — Stop exporting DISPLAY.
foo() { echo hello; }; export -f foo — Export function foo.

Use in #!/bin/sh shebangs to set env for subprocesses: export LC_ALL=C

Originated in Bourne shell (1977) by Stephen Bourne at Bell Labs. Adopted in POSIX.1-1988, with enhancements like -f and -n in Bash (1989) and ksh.

env(1), printenv(1), declare(1), set(1), unset(1)