NAME
tmpnam - create a name for a temporary file
SYNOPSIS
#include <stdio.h>
char *tmpnam(char *s);
DESCRIPTION
The tmpnam() function shall generate a string that is a valid filename
and that is not the same as the name of an existing file. The function
is potentially capable of generating {TMP_MAX} different strings, but
any or all of them may already be in use by existing files and thus not
be suitable return values.
The tmpnam() function generates a different string each time it is
called from the same process, up to {TMP_MAX} times. If it is called
more than {TMP_MAX} times, the behavior is implementation-defined.
The implementation shall behave as if no function defined in this
volume of IEEE Std 1003.1-2001 calls tmpnam().
If the application uses any of the functions guaranteed to be available
if either _POSIX_THREAD_SAFE_FUNCTIONS or _POSIX_THREADS is defined,
the application shall ensure that the tmpnam() function is called with
a non-NULL parameter.
RETURN VALUE
Upon successful completion, tmpnam() shall return a pointer to a
string. If no suitable string can be generated, the tmpnam() function
shall return a null pointer.
If the argument s is a null pointer, tmpnam() shall leave its result in
an internal static object and return a pointer to that object.
Subsequent calls to tmpnam() may modify the same object. If the
argument s is not a null pointer, it is presumed to point to an array
of at least L_tmpnam chars; tmpnam() shall write its result in that
array and shall return the argument as its value.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
Generating a Filename
The following example generates a unique filename and stores it in the
array pointed to by ptr.
#include <stdio.h>
...
char filename[L_tmpnam+1];
char *ptr;
ptr = tmpnam(filename);
APPLICATION USAGE
This function only creates filenames. 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() , open() , tempnam() , tmpfile() , 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 .