TMPFILE(3)                 POSIX Programmer's Manual                TMPFILE(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
       tmpfile -- create a temporary file

SYNOPSIS
       #include <stdio.h>

       FILE *tmpfile(void);

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 tmpfile() function shall create a temporary file and open a
       corresponding stream. The file shall be automatically deleted when all
       references to the file are closed. The file shall be opened as in
       fopen() for update (wb+), except that implementations may restrict the
       permissions, either by clearing the file mode bits or setting them to
       the value S_IRUSR | S_IWUSR.

       In some implementations, a permanent file may be left behind if the
       process calling tmpfile() is killed while it is processing a call to
       tmpfile().

       An error message may be written to standard error if the stream cannot
       be opened.

RETURN VALUE
       Upon successful completion, tmpfile() shall return a pointer to the
       stream of the file that is created.  Otherwise, it shall return a null
       pointer and set errno to indicate the error.

ERRORS
       The tmpfile() function shall fail if:

       EINTR  A signal was caught during tmpfile().

       EMFILE All file descriptors available to the process are currently
              open.

       EMFILE {STREAM_MAX} streams are currently open in the calling process.

       ENFILE The maximum allowable number of files is currently open in the
              system.

       ENOSPC The directory or file system which would contain the new file
              cannot be expanded.

       EOVERFLOW
              The file is a regular file and the size of the file cannot be
              represented correctly in an object of type off_t.

       The tmpfile() function may fail if:

       EMFILE {FOPEN_MAX} streams are currently open in the calling process.

       ENOMEM Insufficient storage space is available.

       The following sections are informative.

EXAMPLES
   Creating aa Temporary File
       The following example creates a temporary file for update, and returns
       a pointer to a stream for the created file in the fp variable.


           #include <stdio.h>
           ...
           FILE *fp;

           fp = tmpfile ();

APPLICATION USAGE
       It should be possible to open at least {TMP_MAX} temporary files during
       the lifetime of the program (this limit may be shared with tmpnam())
       and there should be no limit on the number simultaneously open other
       than this limit and any limit on the number of open file descriptors or
       streams ({OPEN_MAX}, {FOPEN_MAX}, {STREAM_MAX}).

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       Section 2.5, Standard I/O Streams, fopen(), mkdtemp(), 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                           TMPFILE(3)
