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CUSERID(3V)                                                        CUSERID(3V)



NAME
       cuserid - get character login name of the user

SYNOPSIS
       #include <&lt;stdio.h>&gt;

       char *cuserid(s)
       char *s;

DESCRIPTION
       cuserid()  returns  a  pointer  to a string representing the login name
       under which the owner of the current process is logged in.  If s  is  a
       NULL  pointer,  this  string  is placed in an internal static area, the
       address of which is returned.  Otherwise, s is assumed to point  to  an
       array  of  at least L_cuserid characters; the representation is left in
       this array.  The constant L_cuserid is defined in the <&lt;stdio.h>&gt;  header
       file.

SEE ALSO
       cc(1V), ld(1), getlogin(3V), getpwent(3V)

RETURN VALUES
       cuserid()  returns a pointer to the login name on success.  On failure,
       cuserid() returns NULL, and if s is not NULL, places a  null  character
       ('\0') at s[0].

NOTES
       The  internal static area to which cuserid() writes when s is NULL will
       be overwritten by a subsequent call to getpwnam() (see getpwent(3V)).

       A compatibility problem has been identified with  the  cuserid()  func-
       tion.  The traditional version of this library routine in SunOS Release
       3.2 and later releases and all System V releases calls  the  getlogin()
       function, and if it fails uses the getpwuid() function to try to return
       a name associated with the real user ID  associated  with  the  calling
       process.   POSIX.1 requires that the cuserid() function try to return a
       name associated with the effective user ID associated with the  calling
       process.  Although this usually yields the same results, use of set-uid
       programs may yield different results.

       A binding interpretation has  been  issued  by  IEEE  saying  that  the
       POSIX.1  functionality  has to be provided for compliance with POSIX.1.
       However, balloting on the first update to POSIX.1, P1003.1a, has led to
       the  removal of the cuserid() function from the standard.  (This is the
       state in the second recirculation ballot of P1003.1a dated 11  December
       1989.)   The  objections  leading to this resolution had both users and
       implementors arguing for the historical version  and  for  the  version
       specified by POSIX.1.  The only way to reach consensus appears to be to
       remove the function from the standard.

       To further complicate the issue, System V Release 4.0 has kept the tra-
       ditional  version  of cuserid().  XPG3 specifies the POSIX.1 version of
       cuserid(), but the test suite  for  conformance  to  XPG3  promises  to
       accept either implementation.  Both of these are anticipating the final
       approval of P1003.1a as a standard with the cuserid() function removed.

       Since we also expect the cuserid() function  to  be  dropped  from  the
       standard when P1003.1a is approved, SunOS Release 4.1 provides the tra-
       ditional cuserid() function in the C library.  However, for users  that
       need  the  version  specified  by  POSIX.1,  it  is provided in a POSIX
       library available in the System V environment.   This  library  can  be
       accessed by specifying -lposix on the cc(1V) or ld(1) command line.



                                21 January 1990                    CUSERID(3V)