Index: doc/coreutils.info
===================================================================
--- doc/coreutils.info.orig	2012-01-06 18:17:59.000000000 +0100
+++ doc/coreutils.info	2012-04-13 15:46:58.183689004 +0200
@@ -12690,6 +12690,10 @@ and optionally successful, `su' attempts
 `syslog'.)  However, GNU `su' does not check if the user is a member of
 the `wheel' group; see below.
 
+   If the environment variable SU_COMMAND_SAME_SESSION is set, su will
+not open a new session for running a command thus making -c behaves just
+like -C.
+
    The program accepts the following options.  Also see *note Common
 options::.
 
@@ -12698,6 +12702,12 @@ options::.
      Pass COMMAND, a single command line to run, to the shell with a
      `-c' option instead of starting an interactive shell.
 
+`-C COMMAND'
+`--session-command=COMMAND'
+     Pass COMMAND, a single command line to run, to the shell with a
+     `-c' option instead of starting an interactive and do not create
+     a new session for it.
+
 `-f'
 `--fast'
      Pass the `-f' option to the shell.  This probably only makes sense
Index: src/su.c
===================================================================
--- src/su.c.orig	2012-04-13 15:46:58.117690610 +0200
+++ src/su.c	2012-04-13 15:49:11.285454137 +0200
@@ -141,6 +141,9 @@ static bool simulate_login;
 /* If true, change some environment vars to indicate the user su'd to.  */
 static bool change_environment;
 
+/* If true, then don't call setsid() with a command. */
+int same_session = 0;
+
 #ifdef USE_PAM
 static bool _pam_session_opened;
 static bool _pam_cred_established;
@@ -149,6 +152,7 @@ static bool _pam_cred_established;
 static struct option const longopts[] =
 {
   {"command", required_argument, NULL, 'c'},
+  {"session-command", required_argument, NULL, 'C'},
   {"fast", no_argument, NULL, 'f'},
   {"login", no_argument, NULL, 'l'},
   {"preserve-environment", no_argument, NULL, 'p'},
@@ -326,14 +330,29 @@ create_watching_parent (void)
       sigemptyset (&action.sa_mask);
       action.sa_flags = 0;
       sigemptyset (&ourset);
-      if (sigaddset (&ourset, SIGTERM)
-	  || sigaddset (&ourset, SIGALRM)
-	  || sigaction (SIGTERM, &action, NULL)
-	  || sigprocmask (SIG_UNBLOCK, &ourset, NULL))
-	{
+
+      if (!same_session)
+        {
+          if (sigaddset(&ourset, SIGINT) || sigaddset(&ourset, SIGQUIT))
+            {
+              error (0, errno, _("cannot set signal handler"));
+              caught_signal = true;
+            }
+        }
+      if (!caught_signal && (sigaddset(&ourset, SIGTERM)
+                      || sigaddset(&ourset, SIGALRM)
+                      || sigaction(SIGTERM, &action, NULL)
+                      || sigprocmask(SIG_UNBLOCK, &ourset, NULL)))
+        {
 	  error (0, errno, _("cannot set signal handler"));
 	  caught_signal = true;
 	}
+    if (!caught_signal && !same_session && (sigaction(SIGINT, &action, NULL)
+                                     || sigaction(SIGQUIT, &action, NULL)))
+      {
+        error (0, errno, _("cannot set signal handler"));
+        caught_signal = true;
+      }
     }
   if (!caught_signal)
     {
@@ -751,6 +770,8 @@ Change the effective user id and group i
 \n\
   -, -l, --login               make the shell a login shell\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\
@@ -773,6 +794,7 @@ main (int argc, char **argv)
   int optc;
   const char *new_user = DEFAULT_USER;
   char *command = NULL;
+  int request_same_session = 0;
   char *shell = NULL;
   struct passwd *pw;
   struct passwd pw_copy;
@@ -796,6 +818,14 @@ main (int argc, char **argv)
         {
         case 'c':
           command = optarg;
+          if (NULL != getenv ("SU_COMMAND_SAME_SESSION") ||
+              NULL != getenv ("SU_COMMAND_OPENS_SESSION"))
+            request_same_session = 1;
+          break;
+
+        case 'C':
+          command = optarg;
+          request_same_session = 1;
           break;
 
         case 'f':
@@ -868,6 +898,9 @@ main (int argc, char **argv)
     }
 #endif
 
+  if (request_same_session || !command || !pw->pw_uid)
+    same_session = 1;
+
   if (!shell && !change_environment)
     shell = getenv ("SHELL");
   if (shell && getuid () != 0 && restricted_shell (pw->pw_shell))
@@ -890,6 +923,9 @@ main (int argc, char **argv)
 
   change_identity (pw);
 
+  if (!same_session)
+    setsid ();
+
   /* Set environment after pam_open_session, which may put KRB5CCNAME
      into the pam_env, etc.  */