Mastering the export Command: How to View and Set Environment Variables in Linux

export: Display or Set Environment Variables

Function Description

export command is used to export shell variables as environment variables, or export shell functions as environment variables.

When a variable is created, it is not automatically known to subsequently created shell processes. The export command can pass variable values to subsequent shells. When a shell script is invoked, it does not automatically inherit variables defined in the caller unless those variables have been explicitly exported. export can be used to pass one or more variable values to any subsequent script.

Command Syntax

export [options [arguments]]

Option Meanings

-f : indicates that the name in the variable list is a function name

-n : delete the specified environment variable

-p : list all environment variables assigned by the shell

Argument Meaning

Variable: specifies the environment variable to export or delete.

Reference Examples

(1) List all environment variables

[root@cnLinuxer ~]# export -p
declare -x HISTCONTROL="ignoredups"
declare -x HISTSIZE="1000"
declare -x HOME="/root"
declare -x HOSTNAME="cnLinuxer"
declare -x LANG="zh_CN.UTF-8"
declare -x LESSOPEN="||/usr/bin/lesspipe.sh %s"
declare -x LOGNAME="root"
... (output truncated)

(2) Set the value of environment variable HISTSIZE to 1500 [root@cnLinuxer ~]# export HISTSIZE=1500 (3) Add environment variable (JAVA) to ~/.bashrc

PATH=/usr/local/jdk1.7.0/bin:$PATH