I suppose I could have just logged in to my HP-UX computer to confirm.
So now I do that. It indeed has an incompatible version of mktemp that
happens to be even worse than the option that I proposed; here is the
relevant section of the man page.
The name generated by mktemp is the concatenation of a directory name,
a slash (/), the value of the LOGNAME environment variable truncated
to {NAME_MAX} - 6 characters, and the process ID of the invoking
process.
But this is from version 11.11, so I suppose it would be acceptable
not to care about it.
