diff -urNp coreutils-8.1-orig/AUTHORS coreutils-8.1/AUTHORS
--- coreutils-8.1-orig/AUTHORS	2009-11-06 18:04:10.000000000 +0100
+++ coreutils-8.1/AUTHORS	2009-11-20 13:06:26.000000000 +0100
@@ -65,6 +65,7 @@ readlink: Dmitry V. Levin
 rm: Paul Rubin, David MacKenzie, Richard M. Stallman, Jim Meyering
 rmdir: David MacKenzie
 runcon: Russell Coker
+runuser: David MacKenzie, Dan Walsh
 seq: Ulrich Drepper
 sha1sum: Ulrich Drepper, Scott Miller, David Madore
 sha224sum: Ulrich Drepper, Scott Miller, David Madore
diff -urNp coreutils-8.1-orig/man/help2man coreutils-8.1/man/help2man
--- coreutils-8.1-orig/man/help2man	2009-09-23 10:25:44.000000000 +0200
+++ coreutils-8.1/man/help2man	2009-11-20 13:06:26.000000000 +0100
@@ -556,6 +556,9 @@ while (length)
     $include{$sect} .= $content;
 }
 
+# There is no info documentation for runuser (shared with su).
+$opt_no_info = 1 if $program eq 'runuser';
+
 # Refer to the real documentation.
 unless ($opt_no_info)
 {
diff -urNp coreutils-8.1-orig/man/Makefile.am coreutils-8.1/man/Makefile.am
--- coreutils-8.1-orig/man/Makefile.am	2009-11-06 18:04:10.000000000 +0100
+++ coreutils-8.1/man/Makefile.am	2009-11-20 13:06:26.000000000 +0100
@@ -94,6 +94,7 @@ readlink.1:	$(common_dep)	$(srcdir)/read
 rm.1:		$(common_dep)	$(srcdir)/rm.x		../src/rm.c
 rmdir.1:	$(common_dep)	$(srcdir)/rmdir.x	../src/rmdir.c
 runcon.1:	$(common_dep)	$(srcdir)/runcon.x	../src/runcon.c
+runuser.1:	$(common_dep)	$(srcdir)/runuser.x	../src/su.c
 seq.1:		$(common_dep)	$(srcdir)/seq.x		../src/seq.c
 sha1sum.1:	$(common_dep)	$(srcdir)/sha1sum.x	../src/md5sum.c
 sha224sum.1:	$(common_dep)	$(srcdir)/sha224sum.x	../src/md5sum.c
diff -urNp coreutils-8.1-orig/man/runuser.x coreutils-8.1/man/runuser.x
--- coreutils-8.1-orig/man/runuser.x	1970-01-01 01:00:00.000000000 +0100
+++ coreutils-8.1/man/runuser.x	2009-11-20 13:06:26.000000000 +0100
@@ -0,0 +1,12 @@
+[NAME]
+runuser \- run a shell with substitute user and group IDs
+[DESCRIPTION]
+.\" Add any additional description here
+[SEE ALSO]
+.TP
+More detailed Texinfo documentation could be found by command
+.TP
+\t\fBinfo coreutils \(aqsu invocation\(aq\fR\t
+.TP
+since the command \fBrunuser\fR is trimmed down version of command \fBsu\fR.
+.br
diff -urNp coreutils-8.1-orig/README coreutils-8.1/README
--- coreutils-8.1-orig/README	2009-11-06 18:04:10.000000000 +0100
+++ coreutils-8.1/README	2009-11-20 13:06:26.000000000 +0100
@@ -12,10 +12,10 @@ The programs that can be built with this
   factor false fmt fold groups head hostid hostname id install join kill
   link ln logname ls md5sum mkdir mkfifo mknod mktemp mv nice nl nohup
   nproc od paste pathchk pinky pr printenv printf ptx pwd readlink rm rmdir
-  runcon seq sha1sum sha224sum sha256sum sha384sum sha512sum shred shuf
-  sleep sort split stat stdbuf stty su sum sync tac tail tee test timeout
-  touch tr true truncate tsort tty uname unexpand uniq unlink uptime users
-  vdir wc who whoami yes
+  runcon runuser seq sha1sum sha224sum sha256sum sha384sum sha512sum shred
+  shuf sleep sort split stat stdbuf stty su sum sync tac tail tee test
+  timeout touch tr true truncate tsort tty uname unexpand uniq unlink uptime
+  users vdir wc who whoami yes
 
 See the file NEWS for a list of major changes in the current release.
 
diff -urNp coreutils-8.1-orig/src/Makefile.am coreutils-8.1/src/Makefile.am
--- coreutils-8.1-orig/src/Makefile.am	2009-11-20 13:06:00.000000000 +0100
+++ coreutils-8.1/src/Makefile.am	2009-11-20 13:06:26.000000000 +0100
@@ -100,6 +100,7 @@ EXTRA_PROGRAMS = \
   rm		\
   rmdir		\
   runcon	\
+  runuser \
   seq		\
   sha1sum	\
   sha224sum	\
@@ -296,6 +297,10 @@ cp_LDADD += $(copy_LDADD)
 ginstall_LDADD += $(copy_LDADD)
 mv_LDADD += $(copy_LDADD)
 
+runuser_SOURCES = su.c
+runuser_CFLAGS = -DRUNUSER -DAUTHORS="\"David MacKenzie, Dan Walsh\""
+runuser_LDADD = $(LDADD) $(LIB_CRYPT) @LIB_PAM@
+
 remove_LDADD =
 mv_LDADD += $(remove_LDADD)
 rm_LDADD += $(remove_LDADD)
@@ -396,7 +401,7 @@ RELEASE_YEAR = \
   `sed -n '/.*COPYRIGHT_YEAR = \([0-9][0-9][0-9][0-9]\) };/s//\1/p' \
     $(top_srcdir)/lib/version-etc.c`
 
-all-local: su$(EXEEXT)
+all-local: su$(EXEEXT) runuser
 
 installed_su = $(DESTDIR)$(bindir)/`echo su|sed '$(transform)'`
 
diff -urNp coreutils-8.1-orig/src/su.c coreutils-8.1/src/su.c
--- coreutils-8.1-orig/src/su.c	2009-11-20 13:06:00.000000000 +0100
+++ coreutils-8.1/src/su.c	2009-11-20 13:06:26.000000000 +0100
@@ -102,9 +102,15 @@
 #include "error.h"
 
 /* The official name of this program (e.g., no `g' prefix).  */
+#ifndef RUNUSER
 #define PROGRAM_NAME "su"
+#else
+#define PROGRAM_NAME "runuser"
+#endif
 
+#ifndef AUTHORS
 #define AUTHORS proper_name ("David MacKenzie")
+#endif
 
 #if HAVE_PATHS_H
 # include <paths.h>
@@ -142,9 +148,16 @@
 #ifndef USE_PAM
 char *crypt (char const *key, char const *salt);
 #endif
+#ifndef CHECKPASSWD
+#define CHECKPASSWD 1
+#endif
 
 static void run_shell (char const *, char const *, char **, size_t,
-	const struct passwd *)
+        const struct passwd *
+#ifdef RUNUSER
+                       , gid_t *groups, int num_groups
+#endif
+        )
 #ifdef USE_PAM
 	;
 #else
@@ -171,6 +184,10 @@ static struct option const longopts[] =
   {"login", no_argument, NULL, 'l'},
   {"preserve-environment", no_argument, NULL, 'p'},
   {"shell", required_argument, NULL, 's'},
+#ifdef RUNUSER
+  {"group", required_argument, NULL, 'g'},
+  {"supp-group", required_argument, NULL, 'G'},
+#endif
   {GETOPT_HELP_OPTION_DECL},
   {GETOPT_VERSION_OPTION_DECL},
   {NULL, 0, NULL, 0}
@@ -272,10 +289,12 @@ correct_password (const struct passwd *p
   retval = pam_start(PROGRAM_NAME, pw->pw_name, &conv, &pamh);
   PAM_BAIL_P;
 
+#ifndef RUNUSER
   if (getuid() != 0 && !isatty(0)) {
 	fprintf(stderr, "standard in must be a tty\n");
 	exit(1);
   }
+#endif
 
   caller = getpwuid(getuid());
   if(caller != NULL && caller->pw_name != NULL) {
@@ -292,6 +311,11 @@ correct_password (const struct passwd *p
     retval = pam_set_item(pamh, PAM_TTY, tty_name);
     PAM_BAIL_P;
   }
+#ifdef RUNUSER
+  if (getuid() != geteuid())
+    /* safety net: deny operation if we are suid by accident */
+    error(EXIT_FAILURE, 1, "runuser may not be setuid");
+#else
   retval = pam_authenticate(pamh, 0);
   PAM_BAIL_P;
   retval = pam_acct_mgmt(pamh, 0);
@@ -301,6 +325,7 @@ correct_password (const struct passwd *p
     PAM_BAIL_P;
   }
   PAM_BAIL_P;
+#endif
   /* must be authenticated if this point was reached */
   return 1;
 #else /* !USE_PAM */
@@ -382,11 +407,22 @@ modify_environment (const struct passwd 
 /* Become the user and group(s) specified by PW.  */
 
 static void
-change_identity (const struct passwd *pw)
+change_identity (const struct passwd *pw
+#ifdef RUNUSER
+                 , gid_t *groups, int num_groups
+#endif
+        )
 {
 #ifdef HAVE_INITGROUPS
+  int rc = 0;
   errno = 0;
-  if (initgroups (pw->pw_name, pw->pw_gid) == -1) {
+#ifdef RUNUSER
+  if (num_groups)
+    rc = setgroups(num_groups, groups);
+  else
+#endif
+    rc = initgroups(pw->pw_name, pw->pw_gid);
+  if (rc == -1) {
 #ifdef USE_PAM
     pam_close_session(pamh, 0);
     pam_end(pamh, PAM_ABORT);
@@ -433,7 +469,11 @@ pam_copyenv (pam_handle_t *pamh)
 
 static void
 run_shell (char const *shell, char const *command, char **additional_args,
-           size_t n_additional_args, const struct passwd *pw)
+           size_t n_additional_args, const struct passwd *pw
+#ifdef RUNUSER
+           , gid_t *groups, int num_groups
+#endif
+        )
 {
   size_t n_args = 1 + fast_startup + 2 * !!command + n_additional_args + 1;
   char const **args = xnmalloc (n_args, sizeof *args);
@@ -464,7 +504,11 @@ run_shell (char const *shell, char const
 
   child = fork();
   if (child == 0) {  /* child shell */
-  change_identity (pw);
+  change_identity (pw
+#ifdef RUNUSER
+                   , groups, num_groups
+#endif
+          );
   pam_end(pamh, 0);
   if (!same_session)
     setsid ();
@@ -608,6 +652,28 @@ usage (int status)
   else
     {
       printf (_("Usage: %s [OPTION]... [-] [USER [ARG]...]\n"), program_name);
+#ifdef RUNUSER
+      printf (_("\
+Change the effective user id and group id to that of USER.  Only session PAM\n\
+hooks are run, and there is no password prompt.  This command is useful only\n\
+when run as the root user.  If run as a non-root user without privilege\n\
+to set user ID, the command will fail as the binary is not setuid.\n\
+As %s doesn't run auth and account PAM hooks, it runs with lower overhead\n\
+than su.\n\
+\n\
+  -, -l, --login               make the shell a login shell, uses runuser-l\n\
+                               PAM file instead of default one\n\
+  -g --group=group             specify the primary group\n\
+  -G --supp-group=group        specify a supplemental group\n\
+  -c, --command=COMMAND        pass a single COMMAND to the shell with -c\n\
+  --session-command=COMMAND    pass a single COMMAND to the shell with -c\n\
+                               and do not create a new session\n\
+  -f, --fast                   pass -f to the shell (for csh or tcsh)\n\
+  -m, --preserve-environment   do not reset environment variables\n\
+  -p                           same as -m\n\
+  -s, --shell=SHELL            run SHELL if /etc/shells allows it\n\
+"), program_name);
+#else
       fputs (_("\
 Change the effective user id and group id to that of USER.\n\
 \n\
@@ -620,6 +686,7 @@ Change the effective user id and group i
   -p                           same as -m\n\
   -s, --shell=SHELL            run SHELL if /etc/shells allows it\n\
 "), stdout);
+#endif
       fputs (HELP_OPTION_DESCRIPTION, stdout);
       fputs (VERSION_OPTION_DESCRIPTION, stdout);
       fputs (_("\
@@ -641,6 +708,12 @@ main (int argc, char **argv)
   char *shell = NULL;
   struct passwd *pw;
   struct passwd pw_copy;
+#ifdef RUNUSER
+  struct group *gr;
+  gid_t groups[NGROUPS_MAX];
+  int num_supp_groups = 0;
+  int use_gid = 0;
+#endif
 
   initialize_main (&argc, &argv);
   set_program_name (argv[0]);
@@ -655,7 +728,11 @@ main (int argc, char **argv)
   simulate_login = false;
   change_environment = true;
 
-  while ((optc = getopt_long (argc, argv, "c:flmps:", longopts, NULL)) != -1)
+  while ((optc = getopt_long (argc, argv, "c:flmps:"
+#ifdef RUNUSER
+                              "g:G:"
+#endif
+                              , longopts, NULL)) != -1)
     {
       switch (optc)
         {
@@ -685,6 +762,28 @@ main (int argc, char **argv)
           shell = optarg;
           break;
 
+#ifdef RUNUSER
+        case 'g':
+          gr = getgrnam(optarg);
+          if (!gr)
+            error (EXIT_FAILURE, 0, _("group %s does not exist"), optarg);
+          use_gid = 1;
+          groups[0] = gr->gr_gid;
+          break;
+
+        case 'G':
+          num_supp_groups++;
+          if (num_supp_groups >= NGROUPS_MAX)
+            error (EXIT_FAILURE, 0,
+                   _("Can't specify more than %d supplemental groups"),
+                   NGROUPS_MAX - 1);
+          gr = getgrnam(optarg);
+          if (!gr)
+            error (EXIT_FAILURE, 0, _("group %s does not exist"), optarg);
+          groups[num_supp_groups] = gr->gr_gid;
+          break;
+#endif
+
         case_GETOPT_HELP_CHAR;
 
         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
@@ -723,7 +822,20 @@ main (int argc, char **argv)
                           : DEFAULT_SHELL);
   endpwent ();
 
-  if (!correct_password (pw))
+#ifdef RUNUSER
+  if (num_supp_groups && !use_gid)
+  {
+    pw->pw_gid = groups[1];
+    memmove (groups, groups + 1, sizeof(gid_t) * num_supp_groups);
+  }
+  else if (use_gid)
+  {
+    pw->pw_gid = groups[0];
+    num_supp_groups++;
+  }
+#endif
+
+  if (CHECKPASSWD && !correct_password (pw))
     {
 #ifdef SYSLOG_FAILURE
       log_su (pw, false);
@@ -755,7 +867,11 @@ main (int argc, char **argv)
   modify_environment (pw, shell);
 
 #ifndef USE_PAM
-  change_identity (pw);
+  change_identity (pw
+#ifdef RUNUSER
+                   , groups, num_supp_groups
+#endif
+                   );
 #endif
 
   /* error() flushes stderr, but does not check for write failure.
@@ -766,5 +882,9 @@ main (int argc, char **argv)
   if (ferror (stderr))
     exit (EXIT_CANCELED);
 
-  run_shell (shell, command, argv + optind, MAX (0, argc - optind), pw);
+  run_shell (shell, command, argv + optind, MAX (0, argc - optind), pw
+#ifdef RUNUSER
+             , groups, num_supp_groups
+#endif
+             );
 }
diff -urNp coreutils-8.1-orig/tests/misc/help-version coreutils-8.1/tests/misc/help-version
--- coreutils-8.1-orig/tests/misc/help-version	2009-11-14 15:01:44.000000000 +0100
+++ coreutils-8.1/tests/misc/help-version	2009-11-20 13:06:26.000000000 +0100
@@ -34,6 +34,7 @@ expected_failure_status_nohup=125
 expected_failure_status_stdbuf=125
 expected_failure_status_su=125
 expected_failure_status_timeout=125
+expected_failure_status_runuser=125
 expected_failure_status_printenv=2
 expected_failure_status_tty=3
 expected_failure_status_sort=2
@@ -153,6 +154,7 @@ seq_args=10
 sleep_args=0
 su_args=--version
 stdbuf_args="-oL true"
+runuser_args=--version
 timeout_args=--version
 
 # I'd rather not run sync, since it spins up disks that I've
diff -urNp coreutils-8.1-orig/tests/misc/invalid-opt coreutils-8.1/tests/misc/invalid-opt
--- coreutils-8.1-orig/tests/misc/invalid-opt	2009-10-26 10:05:25.000000000 +0100
+++ coreutils-8.1/tests/misc/invalid-opt	2009-11-20 13:06:26.000000000 +0100
@@ -37,6 +37,7 @@ my %exit_status =
     sort => 2,
     stdbuf => 125,
     su => 125,
+    runuser => 125,
     test => 0,
     timeout => 125,
     true => 0,