unset Linux Command Guide
The Linux unset command is used to remove environment variables. It allows you to unset a specific variable or multiple variables at once. When you unset a variable, its value and existence are deleted from the environment. This can help manage your environment and prevent potential conflicts or unwanted behavior in your shell sessions. Understanding how to use unset properly can help you maintain a clean and efficient working environment on your Linux system.
unset Syntax:
Section titled “unset Syntax:”unset [option] [parameter]Options:
Section titled “Options:”| Option | Description |
|---|---|
| -v | Print each variable name before unset. |
| -f | Unsets the function names only. |
| -n | Treats each name as a variable name, even if it contains a symbol. |
| -a | Unsets all variable names indexed by an array name. |
Parameters:
Section titled “Parameters:”| Parameter | Description |
|---|---|
| name | Specifies the name of the variable to unset. |
| -v name | Unsets the variable name. |
| -f name | Unsets the function name. |
| -n name | Treats the given name as a variable name. |
| -a name | Unsets all variables indexed by array name. |
unset Command Samples:
Section titled “unset Command Samples:”Unset an Environment Variable
Section titled “Unset an Environment Variable”unset VARIABLE_NAMERemoves the specified environment variable from the current environment.
Unset Multiple Environment Variables
Section titled “Unset Multiple Environment Variables”unset VAR1 VAR2 VAR3Unsets multiple environment variables in a single command.
Unset All Variables Starting with a Prefix
Section titled “Unset All Variables Starting with a Prefix”unset VAR_PREFIX*Removes all environment variables that start with a specific prefix.
Unset a Function
Section titled “Unset a Function”unset -f FUNCTION_NAMEDeletes the specified function from the current shell session.
Unset a Readonly Variable
Section titled “Unset a Readonly Variable”unset READONLY_VARCan unset a variable that was previously set as readonly.
Unset a Variable in a Subshell
Section titled “Unset a Variable in a Subshell”(subshell) unset VAR_IN_SUBSHELLUnset a variable within a subshell environment.
Unset All Variables
Section titled “Unset All Variables”unset *Removes all variables and functions from the current shell session.
unset FAQ:
Section titled “unset FAQ:”How do I use unset in Linux?
Section titled “How do I use unset in Linux?”To use the unset command in Linux, execute the following command:
unset variable_nameWhat does unset do in Linux?
Section titled “What does unset do in Linux?”The unset command in Linux is used to remove variables or functions.
How can I unset multiple variables in Linux?
Section titled “How can I unset multiple variables in Linux?”To unset multiple variables in Linux, you can specify them separated by a space in a single unset command.
unset var1 var2 var3Can unset be used to unset functions in Linux?
Section titled “Can unset be used to unset functions in Linux?”Yes, the unset command can be used to unset functions in Linux.
unset -f function_nameHow can I unset all variables in Linux?
Section titled “How can I unset all variables in Linux?”To unset all variables in Linux, you can use the following command:
unset $(compgen -v)Is there a way to unset a readonly variable in Linux?
Section titled “Is there a way to unset a readonly variable in Linux?”Yes, you can unset a readonly variable in Linux by using the -f option.
unset -f readonly_variableApplications of the unset command
Section titled “Applications of the unset command”- Clearing environment variables
- Removing elements from an array
- Unsetting variables in a script or terminal session