setreuid(3-BSD)   MISC. REFERENCE MANUAL PAGES    setreuid(3-BSD)



NAME
     setreuid - set real and effective user IDs

SYNOPSIS
     cc [ flag... ] file ... -lucb
     int setreuid(ruid, euid)
     int ruid, euid;

DESCRIPTION
     setreuid is used to set the real and effective user  IDs  of
     the calling process.  If ruid is -1, the real user ID is not
     changed; if euid  is  -1,  the  effective  user  ID  is  not
     changed.  The real and effective user IDs may be set to dif-
     ferent values in the same call.  If the effective user ID of
     the  calling process is super-user, the real user ID and the
     effective user ID can be set to any  legal  value.   If  the
     effective  user ID of the calling process is not super-user,
     either the real user ID can be set to the effective user ID,
     or  the  effective  user  ID  can either be set to the saved
     set-user ID from execv or the real user ID. Note: if a  set-
     UID  process sets its effective user ID to its real user ID,
     it can still set its effective user ID  back  to  the  saved
     set-user  ID.  In  either case, if the real user ID is being
     changed (that is, if ruid is not -1), or the effective  user
     ID  is  being  changed to a value not equal to the real user
     ID, the saved set-user ID is set equal to the new  effective
     user ID.

RETURN VALUE
     Upon successful completion, a value of 0 is returned.   Oth-
     erwise,  a value of -1 is returned and errno is set to indi-
     cate the error.

ERRORS
     setreuid will fail and neither  of  the  user  IDs  will  be
     changed if:

     EPERM          The calling process's effective  user  ID  is
                    not  the  super-user  and a change other than
                    changing the real user ID  to  the  effective
                    user ID, or changing the effective user ID to
                    the real user ID or the  saved  set-user  ID,
                    was specified.

SEE ALSO
     setregid(3)   exec(2),   getuid(2),   setuid(2)    in    the
     Programmer's Reference Manual.








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