SETUID(2) UNIX Programmer's Manual SETUID(2) NAME setuid, seteuid,setgid,setegid - set user and group ID SYNOPSIS #include #include _i_n_t setuid(uid) uid_t uid _i_n_t seteuid(euid) uid_t euid _i_n_t setgid(gid) gid_t gid _i_n_t setegid(egid) gid_t egid DESCRIPTION The setuid function sets the real and effective user IDs and the saved set-user-ID of the current process to the speci- fied value. The setuid function is permitted if the speci- fied ID is equal to the real user ID of the process, or if the effective user ID is that of the super user. The setgid function sets the real and effective group IDs and the saved set-group-ID of the current process to the specified value. The setgid function is permitted if the specified ID is equal to the real group ID of the process, or if the effective user ID is that of the super user. The seteuid function (setegid) sets the effective user ID (group ID) of the current process. The effective user ID may be set to the value of the real user ID or the saved set-user-ID (see intro(2) and execve(2); in this way, the effective user ID of a set-user-ID executable may be toggled by switching to the real user ID, then re-enabled by revert- ing to the set-user-ID value. Similarly, the effective group ID may be set to the value of the real group ID or the saved set-user-ID. RETURN VALUES Upon success, these functions return 0; otherwise -1 is returned. If the user is not the super user, or the uid specified is not the real, effective ID, or saved ID, these functions Printed 11/26/99 December 3, 1997 1 SETUID(2) UNIX Programmer's Manual SETUID(2) return -1. SEE ALSO getuid(2), getgid(2) STANDARDS The setuid and setgid functions are compliant with the IEEE Std 1003.1-1988 (``POSIX'') specification with _POSIX_SAVED_IDS not defined. The seteuid and setegid func- tions are extensions based on the POSIX concept of _POSIX_SAVED_IDS , and have been proposed for a future revi- sion of the standard. Printed 11/26/99 December 3, 1997 2