TMPNAM(3)                  POSIX Programmer's Manual                 TMPNAM(3)



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

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 cchhaarrs; 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 aa 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 .



IEEE/The Open Group                  2017                            TMPNAM(3)
