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().
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.
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