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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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TMPFILE(3P) POSIX Programmer's Manual TMPFILE(3P)
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.
tmpfile — create a temporary file
#include <stdio.h>
FILE *tmpfile(void);
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.
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.
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.
Creating a 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 ();
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}).
None.
None.
Section 2.5, Standard I/O Streams, fopen(3p), mkdtemp(3p),
tmpnam(3p), unlink(3p)
The Base Definitions volume of POSIX.1‐2017, stdio.h(0p)
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(3P)
Pages that refer to this page: stdio.h(0p), exit(3p), mkdtemp(3p), stdin(3p), tempnam(3p), tmpnam(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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