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TEMPNAM(3P) POSIX Programmer's Manual TEMPNAM(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.
tempnam — create a name for a temporary file
#include <stdio.h>
char *tempnam(const char *dir, const char *pfx);
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.
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.
The tempnam() function shall fail if:
ENOMEM Insufficient storage space is available.
The following sections are informative.
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);
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.
None.
The tempnam() function may be removed in a future version.
fopen(3p), free(3p), mkdtemp(3p), open(3p), tmpfile(3p), tmpnam(3p),
unlink(3p)
The Base Definitions volume of POSIX.1‐2008, stdio.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 2013 TEMPNAM(3P)
Pages that refer to this page: stdio.h(0p), tmpnam(3p)