MKSTEMP(3P)                                         POSIX Programmer's Manual                                        MKSTEMP(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       mkstemp - make a unique filename

SYNOPSIS
       #include <stdlib.h>

       int mkstemp(char *template);


DESCRIPTION
       The mkstemp() function shall replace the contents of the string pointed to by template by a unique filename, and return a
       file descriptor for the file open for reading and writing.  The  function  thus  prevents  any  possible  race  condition
       between  testing  whether the file exists and opening it for use. The string in template should look like a filename with
       six trailing 'X' s; mkstemp() replaces each 'X' with a character from the portable filename character set. The characters
       are  chosen  such  that  the  resulting  name  does  not  duplicate the name of an existing file at the time of a call to
       mkstemp().

RETURN VALUE
       Upon successful completion, mkstemp() shall return an open file descriptor. Otherwise, -1 shall be returned if  no  suit-
       able file could be created.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
   Generating a Filename
       The following example creates a file with a 10-character name beginning with the characters "file" and opens the file for
       reading and writing. The value returned as the value of fd is a file descriptor that identifies the file.


              #include <stdlib.h>
              ...
              char template[] = "/tmp/fileXXXXXX";
              int fd;


              fd = mkstemp(template);

APPLICATION USAGE
       It is possible to run out of letters.

       The mkstemp() function need not check to determine whether the filename part of template exceeds  the  maximum  allowable
       filename length.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       getpid(), open(), tmpfile(), tmpnam(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>

COPYRIGHT
       Portions  of  this  text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for
       Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6,  Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open  Group
       Standard   is   the   referee   document.   The   original   Standard   can   be   obtained  online  at  http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                   MKSTEMP(3P)