Mastering the unset Command: How to Delete Variables and Functions in Linux

unset: Delete Variables or Functions

Function Description

The unset command is used to delete defined shell variables (including environment variables) and shell functions. It cannot delete shell variables or environment variables that have the read‑only attribute.

Command Syntax

unset [options] [name ...]

Option Meanings

-f : delete only functions

-v : delete only variables (excluding read‑only variables)

-n : delete variable names that have the reference attribute (if this option is present)

Parameter Meaning

name (optional): the variable or function to delete.

Reference Example

// (1) Set environment variable
# ag="df -h"

// (2) Use environment variable
$ ag
# (output of df -h omitted for brevity)

// (3) View current environment variables
set
# (output omitted for brevity)

// (4) Delete environment variable
unset ag

// (5) Delete function
function show_result(){ echo 'Last Command Return: $?'; }
unset -f show_result