$ ls -l file*
ls: file*: No such file or directory
$ ./test.pl > /dev/null
$ ls -l file*
-rw-r--r--  1  19456 Jul 24 22:46 file:memdb2?mode=memory&cache=shared
$ ./test3.pl > /dev/null
$ ls -l file*
-rw-r--r--  1  36864 Jul 24 22:46 file:memdb2?mode=memory&cache=shared