NAME
mkstemp - make a unique filename
SYNOPSIS
#include <stdlib.h>
int mkstemp(char *template);
DESCRIPTION
The mkstemp() function shall replace the contents of the string pointed
to by template by a unique filename, and return a file descriptor for
the file open for reading and writing. The function thus prevents any
possible race condition between testing whether the file exists and
opening it for use. The string in template should look like a filename
with six trailing ’X’ s; mkstemp() replaces each ’X’ with a character
from the portable filename character set. The characters are chosen
such that the resulting name does not duplicate the name of an existing
file at the time of a call to mkstemp().
RETURN VALUE
Upon successful completion, mkstemp() shall return an open file
descriptor. Otherwise, -1 shall be returned if no suitable file could
be created.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
Generating a Filename
The following example creates a file with a 10-character name beginning
with the characters "file" and opens the file for reading and writing.
The value returned as the value of fd is a file descriptor that
identifies the file.
#include <stdlib.h>
...
char template[] = "/tmp/fileXXXXXX";
int fd;
fd = mkstemp(template);
APPLICATION USAGE
It is possible to run out of letters.
The mkstemp() function need not check to determine whether the filename
part of template exceeds the maximum allowable filename length.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
getpid() , open() , tmpfile() , tmpnam() , the Base Definitions volume
of IEEE Std 1003.1-2001, <stdlib.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 .