TEMPNAM(3)                 POSIX Programmer's Manual                TEMPNAM(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
       tempnam -- create a name for a temporary file

SYNOPSIS
       #include <stdio.h>

       char *tempnam(const char *dir, const char *pfx);

DESCRIPTION
       The tempnam() function shall generate a pathname that may be used for a
       temporary file.

       The tempnam() function allows the user to control the choice of a
       directory. The dir argument points to the name of the directory in
       which the file is to be created. If dir is a null pointer or points to
       a string which is not a name for an appropriate directory, the path
       prefix defined as P_tmpdir in the <stdio.h> header shall be used. If
       that directory is not accessible, an implementation-defined directory
       may be used.

       Many applications prefer their temporary files to have certain initial
       letter sequences in their names. The pfx argument should be used for
       this. This argument may be a null pointer or point to a string of up to
       five bytes to be used as the beginning of the filename.

       Some implementations of tempnam() may use tmpnam() internally. On such
       implementations, if called more than {TMP_MAX} times in a single
       process, the behavior is implementation-defined.

RETURN VALUE
       Upon successful completion, tempnam() shall allocate space for a
       string, put the generated pathname in that space, and return a pointer
       to it. The pointer shall be suitable for use in a subsequent call to
       free().  Otherwise, it shall return a null pointer and set errno to
       indicate the error.

ERRORS
       The tempnam() function shall fail if:

       ENOMEM Insufficient storage space is available.

       The following sections are informative.

EXAMPLES
   Generating aa Pathname
       The following example generates a pathname for a temporary file in
       directory /tmp, with the prefix file.  After the pathname has been
       created, the call to free() deallocates the space used to store the
       pathname.


           #include <stdio.h>
           #include <stdlib.h>
           ...
           const char *directory = "/tmp";
           const char *fileprefix = "file";
           char *file;

           file = tempnam(directory, fileprefix);
           free(file);

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(), mkdtemp(), or mkstemp()
       functions instead of the obsolescent tempnam() function.

RATIONALE
       None.

FUTURE DIRECTIONS
       The tempnam() function may be removed in a future version.

SEE ALSO
       fopen(), free(), mkdtemp(), open(), tmpfile(), tmpnam(), 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                           TEMPNAM(3)
