On SunOS 5.5.1, the filenames are of the form /var/tmp/stmAAAa003M_aa,
and the files are typically smaller.
The M_ part, at least, appears to change from run to run, but it
doesn't change within a run.
Solaris 5.5.1 sort doesn't check for symlinks before it opens the file;
I have successfully overwritten a file in my home dir this way.
This is similar to the gcc bug.
Kragen