The variable name.
Set to true to only return local environment variables (set by the operating system or putenv).
Returns the value of the environment variable varname, or false if the environment variable varname does not exist. If varname is omitted, all environment variables are returned as associative array.
If PHP is running in a SAPI such as Fast CGI, this function will always return the value of an environment variable set by the SAPI, even if putenv has been used to set a local environment variable of the same name. Use the local_only parameter to return the value of locally-set environment variables.
|The varname can now be omitted to retrieve an associative array of all environment variables.
|The local_only parameter has been added.