TMPDIR environment variable disappears when using the pro command.

TMPDIR environment variable disappears when using the pro command.
Running progress after setting the TMPDIR environment variable, the statement:

DISPLAY OS-GETENV("TMPDIR").

displays the unknown value '?'
If I shell out to linux without from the Procedure Editor and executing:

echo $TMPDIR

displays nothing!
Exiting the Progress Session and executing:

echo $TMPDIR

from the command prompt displays the correct value.
Same behavior observed using several flavors of Linux.

A workaround is not to run the _progres executable owned by root and to copy it to another directory as yourself making the _progres executable not owned by root anymore, then the TMPDIR value will be preserved.