Uniquely identifying a user: is it possible?

[Karl Fox]

My UNIX-PC (3.51+Development) *does* have getpgrp().  I tried this quick
hack and haven't been able to make it fail yet.  It works while su'd,
nohup'ed and totally redirected.

# include	<sys/types.h>
# include	<utmp.h>

# define	SO	"\033[7m"
# define	SE	"\033[m"

main()
    {
    extern struct utmp *getutent();

    register int pgrp = getpgrp();
    register struct utmp *up;

    while (up = getutent())
	printf("%s%8s %4s %12s %5d %d %d/%d%s\n",
		pgrp == up -> ut_pid ? SO : "",
		up -> ut_user,
		up -> ut_id,
		up -> ut_line,
		up -> ut_pid,
		up -> ut_type,
		up -> ut_exit.e_termination,
		up -> ut_exit.e_exit,
		pgrp == up -> ut_pid ? SE : "");
    }
--
Karl Fox, Morning Star Technologies               karl at MorningStar.Com