TMPNAM(3)						     Linux Programmer's Manual							 TMPNAM(3)

NAME

       tmpnam, tmpnam_r - create a name for a temporary file

SYNOPSIS

       #include <stdio.h>

       char *tmpnam(char *s);

DESCRIPTION

       The  tmpnam()  function	returns  a pointer to a string that is a valid filename, and such that a file with this name did not exist at some
       point in time, so that naive programmers may think it a suitable name for a temporary file.  If the argument s is NULL this name is  gener-
       ated in an internal static buffer and may be overwritten by the next call to tmpnam().  If s is not NULL, the name is copied to the charac-
       ter array (of length at least L_tmpnam) pointed to by s and the value s is returned in case of success.

       The pathname that is created, has a directory prefix P_tmpdir.  (Both L_tmpnam and P_tmpdir are defined in <stdio.h>, just like the TMP_MAX
       mentioned below.)

RETURN VALUE

       The tmpnam() function returns a pointer to a unique temporary filename, or NULL if a unique name cannot be generated.

ERRORS

       No errors are defined.

CONFORMING TO

       SVr4, 4.3BSD, C89, C99, POSIX.1-2001.  POSIX.1-2008 marks tmpnam() as obsolete.

NOTES

       The  tmpnam()  function generates a different string each time it is called, up to TMP_MAX times.  If it is called more than TMP_MAX times,
       the behavior is implementation defined.

       Although tmpnam() generates names that are difficult to guess, it is nevertheless possible that between the time that  tmpnam()	returns  a
       pathname,  and  the  time  that	the program opens it, another program might create that pathname using open(2), or create it as a symbolic
       link.  This can lead to security holes.	To avoid such possibilities, use the open(2) O_EXCL flag to open the pathname.	Or better yet, use
       mkstemp(3) or tmpfile(3).

       Portable  applications  that use threads cannot call tmpnam() with a NULL argument if either _POSIX_THREADS or _POSIX_THREAD_SAFE_FUNCTIONS
       is defined.

       A POSIX draft proposed to use a function tmpnam_r() defined by

	   char *
	   tmpnam_r(char *s)
	   {
	       return s ? tmpnam(s) : NULL;
	   }

       apparently as a warning not to use NULL.  A few systems implement it.  To get a glibc prototype for this function  from	<stdio.h>,  define
       _SVID_SOURCE or _BSD_SOURCE (before including any header file).

BUGS

       Never use this function.  Use mkstemp(3) or tmpfile(3) instead.

SEE ALSO

       mkstemp(3), mktemp(3), tempnam(3), tmpfile(3)

COLOPHON

       This  page is part of release 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

								    2010-09-10								 TMPNAM(3)