This is correct (though of course a decent `mktempd` script will deal with the listed problems or crash loudly on failure), and there are even more reasons to avoid /tmp.

Unfortunately, it is one of the very few directories that are somewhat POSIX-"guaranteed" writable by a non-root user and the fact that on modern systems it is usually mounted on a tmpfs makes it very attractive for pure POSIX usage without rich array support.

If you have mount permissions, of course, you should tell your `mktempd` to base its directory on a private tmpfs.