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 filename has been
created, the call to free() deallocates the space used to store the
filename.
#include <stdio.h>
#include <stdlib.h>
...
char *directory = "/tmp";
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.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
fopen() , free() , open() , tmpfile() , tmpnam() , unlink() , the Base
Definitions volume of IEEE Std 1003.1-2001, <stdio.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .