How to create a temporary file with portable shell in a secure way?

Question

I want to create a temporary file in POSIX shell (/bin/sh).

I found out that mktemp(1) doens\'t exist on my AIX box, and according to How port

Answer 1

Got here from google for portable mktemp. My needs are less secure than OP's, so I ended up just using the script's PID:

tempx=/tmp/mytemp.$$