ultrix man page for setreuid

setreuid(2)							System Calls Manual						       setreuid(2)

Name
       setreuid - set real and effective user ID's

Syntax
       setreuid(ruid, euid)
       intruid, euid;

Description
       The  real  and  effective  user	ID's of the current process are set according to the arguments.  If ruid or euid is -1, the current uid is
       filled in by the system.

Return Values
       Upon successful completion, a value of zero (0) is returned.  Otherwise, a value of -1 is returned and errno is set to indicate the error.

Environment
       BSD
       If the process is superuser, or and matches with the real user ID, the effective user ID, or the saved set-user-id (as described in ), then
       the real, effective, and the saved set-user-id are set to and respectively.

       POSIX
       SYSTEM-FIVE
       When  your  program  is	compiled  in the POSIX or SYSTEM-FIVE mode, if both arguments to are -1, the system call returns a value of -1 and
       errno is set to [EINVAL].

       The following semantics apply when using the function:

       If the process is the superuser, the real, effective, and saved set-user-id (as described in ) are set to and respectively.

       If the process is not the superuser, but the and matches with the real user ID, the effective user ID (only  in	the  SYSTEM-FIVE  and  BSD
       environments), or the saved set-user-id, then the effective ID is set to The  real user ID and the saved set-user-id are left unchanged.

Diagnostics
       [EPERM]	      The  current  process is not the superuser and the and specified does not match with the real user ID, the effective user ID
		      (only in SYSTEM-FIVE and BSD environment), or the saved set-user-id.

See Also
       getuid(2), setregid(2), setuid(3)

																       setreuid(2)