ultrix man page for setregid

setregid(2)							System Calls Manual						       setregid(2)

Name
       setregid - set real and effective group ID

Syntax
       setregid(rgid, egid)
       int rgid, egid;

Description
       The real and effective group ID's of the current process are set to the arguments.

       Supplying a value of -1 for either the real or effective group ID forces the system to substitute the current ID for the -1 parameter.

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

       POSIX
       SYSTEM-FIVE
       When your program is compiled in POSIX or SYSTEM-FIVE mode, the following semantics apply when using the function.

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

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

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.

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

See Also
       getgid(2), setreuid(2), setgid(3)

																       setregid(2)