SETUID(2)                        System Calls                        SETUID(2)




NAME

       setuid, seteuid, setgid, setegid, - set user and group ID


SYNOPSIS

       #include <sys/types.h>
       #include <unistd.h>

       int setuid (uid_t uid);
       int seteuid (uid_t euid);
       int setgid (gid_t gid);
       int setegid (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 specified value.  The  setuid
       function  is permitted if the specified 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 sets the effective user ID (group ID) of the cur-
       rent 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 tog-
       gled  by switching to the real user ID, then re-enabled by reverting 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 return -1.


SEE ALSO

       getuid(2), getgid(2)


STANDARDS

       The setuid and setgid functions are compliant with the POSIX  1003.1-88
       specification with _POSIX_SAVED_IDS not defined.  The seteuid and sete-
       gid  functions  are  extensions  based  on   the   POSIX   concept   of
       _POSIX_SAVED_IDS,  and  have been proposed for a future revision of the
       standard.



GNO                             16 January 1996                      SETUID(2)

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