PROLOG

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

NAME

       tmpnam — create a name for a temporary file

SYNOPSIS

       #include <stdio.h>

       char *tmpnam(char *s);

DESCRIPTION

       The  functionality  described  on  this  reference  page is aligned with the ISO C standard. Any conflict
       between the requirements described  here  and  the  ISO C  standard  is  unintentional.  This  volume  of
       POSIX.1‐2017 defers to the ISO C standard.

       The  tmpnam()  function  shall  generate a string that is a valid pathname that does not name an existing
       file. The function is potentially capable of generating {TMP_MAX} different strings, but any  or  all  of
       them may already be in use by existing files and thus not be suitable return values.

       The  tmpnam()  function  generates a different string each time it is called from the same process, up to
       {TMP_MAX} times. If it is called more than {TMP_MAX} times, the behavior is implementation-defined.

       The implementation shall behave as if  no  function  defined  in  this  volume  of  POSIX.1‐2017,  except
       tempnam(), calls tmpnam().

       The tmpnam() function need not be thread-safe if called with a NULL parameter.

RETURN VALUE

       Upon  successful  completion,  tmpnam()  shall return a pointer to a string. If no suitable string can be
       generated, the tmpnam() function shall return a null pointer.

       If the argument s is a null pointer, tmpnam() shall leave its result in an  internal  static  object  and
       return a pointer to that object. Subsequent calls to tmpnam() may modify the same object. If the argument
       s is not a null pointer, it is presumed to point to an array of at least L_tmpnam chars;  tmpnam()  shall
       write its result in that array and shall return the argument as its value.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

   Generating a Pathname
       The following example generates a unique pathname and stores it in the array pointed to by ptr.

           #include <stdio.h>
           ...
           char pathname[L_tmpnam+1];
           char *ptr;

           ptr = tmpnam(pathname);

APPLICATION USAGE

       This  function  only  creates  pathnames. It is the application's responsibility to create and remove the
       files.

       Between the time a pathname is created and the file is opened, it is possible for some other  process  to
       create a file with the same name.  Applications may find tmpfile() more useful.

       Applications  should  use  the  tmpfile(),  mkstemp(),  or mkdtemp() functions instead of the obsolescent
       tmpnam() function.

RATIONALE

       None.

FUTURE DIRECTIONS

       The tmpnam() function may be removed in a future version.

SEE ALSO

       fopen(), open(), mkdtemp(), tempnam(), tmpfile(), unlink()

       The Base Definitions volume of POSIX.1‐2017, <stdio.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .