euser - display the effective user name, SysV-ish

[John F. Haugh II]

In article <37612 at sgi.SGI.COM> jmb at patton.sgi.com (Jim Barton) writes:
>Why waste time with this?  The system V 'id' command does the
>same thing!  And, it's standard!

It isn't standard under BSD, and the version on AIX doesn't support
concurrent groups.

This version [ the one attached below ] should resolve all of those
problems.  And its public domain, so you can rip it off and send it
out with your BSD port.

Enjoy.
--
/*
 * id - print current process identification information
 *
 * This program was written by John F. Haugh II (jfh at rpp386.UUCP)
 * on 7/9/89 and hereby placed into the public domain.
 *
 * Syntax:
 *	id
 * Synopsis:
 *	Print the current process identifiers.  This includes the
 *	UID, GID, effective-UID and effective-GID.  In environment
 *	where concurrent groupsets exist, the list of groups in
 *	the concurrent groupset is printed as well.
 *
 * Notes:
 *	Straightforward implementation.  Get the IDs and print
 *	them out.  We key on the #define NGROUPS to decide if
 *	concurrent groups exist.  This may have to be changed to
 *	something more intelligent.
 */

#include <sys/types.h>
#include <stdio.h>
#include <grp.h>
#include <pwd.h>

main (argc, argv)
int	argc;
char	**argv;
{
#ifdef	NGROUPS
	int	groups[NGROUPS];
	int	ngroups;
#endif
	int	id;
	int	i;
	struct	passwd	*pw,
			*getpwuid();
	struct	group	*gr,
			*getgrgid();

	if (pw = getpwuid (id = getuid ()))
		printf ("uid=%d(%s)", id, pw->pw_name);
	else
		printf ("uid=%d", id);

	if (gr = getgrgid (id = getgid ()))
		printf (" gid=%d(%s)", id, gr->gr_name);
	else
		printf (" gid=%d", id);

	if (getuid () != geteuid ()) {
		if (pw = getpwuid (id = geteuid ()))
			printf (" euid=%d(%s)", id, pw->pw_name);
		else
			printf (" euid=%d", id);
	}
	if (getgid () != getegid ()) {
		if (gr = getgrgid (id = getegid ()))
			printf (" egid=%d(%s)", id, gr->gr_name);
		else
			printf (" egid=%d", id);
	}
#ifdef	NGROUPS
	if ((ngroups = getgroups (NGROUPS, groups)) != -1) {
		printf (" groupset=(");
		for (i = 0;i < ngroups;i++) {
			if (i)
				putchar (' ');

			if (gr = getgrgid (groups[i]))
				printf ("%s", groups[i], gr->gr_name);
			else
				printf ("%d", groups[i]);
		}
		putchar (')');
	}
#endif
	putchar ('\n');
}
-- 
John F. Haugh II                        +-Quote of the month club: ------------
VoiceNet: (512) 832-8832   Data: -8835  | "Computer security is to information
InterNet: jfh at rpp386.cactus.org         |  control as a chastity belt is to
UucpNet : <backbone>!bigtex!rpp386!jfh  +- birth control"    -- Doug Steves  --