The DG/UX and Tru64 man pages write: If environ has been modified by anything other than the putenv(3), getenv(3), or clearenv() functions, then clearenv() will return an error and the process environment will remain unchanged.
The DG/UX and Tru64 manpages write: If environ has been modified by anything other than the putenv(), getenv(), or clearenv() functions, then clearenv() will return an error and the process environment will remain unchanged.