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

       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 a 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 .