### 36.7 Environment Variables

Built-in Function: getenv (var)

  Return the value of the environment variable var. For example,

      getenv ("PATH")

  returns a string containing the value of your path.

  See also: setenv, unsetenv.

Built-in Function: setenv (var, value)
Built-in Function: setenv (var)
Built-in Function: putenv (…)

  Set the value of the environment variable var to value.

  If no value is specified then the variable will be assigned the null string.

  See also: unsetenv, getenv.

Built-in Function: status = unsetenv (var)

  Delete the environment variable var.

  Return 0 if the variable was deleted, or did not exist, and -1 if an error occurred.

  See also: setenv, getenv.

Built-in Function: homedir = get_home_directory ()

  Return the current home directory.

  On most systems, this is equivalent to `getenv ("HOME")`. On Windows systems, if the environment variable `HOME` is not set then it is equivalent to `fullfile (getenv ("HOMEDRIVE"), getenv ("HOMEPATH"))`

  See also: getenv.