set varname set varname = value set varname = set To unset an environment variable, use ' set varname=', i.e., set it to an empty string. There shall be no spaces before and after the '=' sign. To set (or change) a environment variable, use command ' set varname= value'. To display a particular variable, use command ' set varname', or ' echo % varname%': // Display a particular variable set COMPUTERNAME COMPUTERNAME=xxxxxx // or, use 'echo' command with variable name enclosed within a pair of '%' echo %COMPUTERNAME% COMPUTERNAME=xxxxxx Set/Unset/Change an Environment Variable for the 'Current' CMD Session Pay particular attention to the variable called PATH. Try issuing a ' set' command on your system, and study the environment variables listed. To list ALL the environment variables and their values, start a CMD and issue the command ' set', as follows, // Display all the variables (in NAME=VALUE pairs) set COMPUTERNAME=xxxxxxx Display Environment Variables and their Values They are typically named in uppercase, with words joined with underscore ( _), e.g., JAVA_HOME.

(Windows) HOMEDRIVE, HOMEPATH: Current user's home directory.Įnvironment Variables in Windows are NOT case-sensitive (because the legacy DOS is NOT case-sensitive).

COMPUTENAME, USERNAME: stores the computer and current user name.

PATH: the most frequently-used environment variable, which stores a list of directories to search for executable programs.

Environment variables are useful to store system-wide values, for examples,

Environment variables are global system variables accessible by all the processes/users running under the Operating System (OS), such as Windows, macOS and Linux.

Mac os list environment variables