GDSFILT hangs during scanning when TMPDIR is not defined

A client reported a problem in which GDSFILT Linux and Solaris hangs during the scanning phase and creating a NUL file.

We found that the system variable TMPDIR was not defined on the system. User must make sure that the variable is set to a valid folder name and the folder has write permission.
If TMPDIR is not defined, the program will make use of /tmp so this directory must have write permission as well.