setuid

   With POSIX IDs disabled, implemented for program portability and
   serves no function. It returns 0 (to indicate success).

   With POSIX IDs enabled, sets the user IDs.

   Format

     #include  <types.h>

     #include  <unistd.h>

     int setuid  (__uid_t uid); (_DECC_V4_SOURCE)

     uid_t setuid  (uid_t uid); (not _DECC_V4_SOURCE)
 

Additional information available:

Argument        Description     Return_Values