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 generated 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 character 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.

ATTRIBUTES

   Multithreading (see pthreads(7))
       The  tmpnam()  function  is  thread-safe  with  exceptions.   It is not thread-safe if called with a NULL
       parameter.

       The tmpnam_r() function is thread-safe.

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 3.54 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/.

                                                   2013-06-21                                          TMPNAM(3)