User ID and user group ID

The main function is

# Include <sys/types. h> # Include <Unistd. h> Uid_t getuid (  Void  ); Gid_t getgid (  Void  ); Uid_t gettuid (  Void  ); Gid_t getegid (  Void  );  // Change ID  Int  Setuid (uid_t UID );  Int  Setgid (gid_t GID );  //  Exchange actual users and valid user IDs  Int  Setreuid (uid_t ruid, uid_t EUID );  Int  Setregid (gid_t rgid, gid_t EGID );  //  Change valid user ID  Int  Seteuid (uid_t EUID );  Int Setegid (gid_t EGID );

 

User ID and user group ID