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

       tmpnam, tmpnam_r - create a name for a temporary file

       #include <stdio.h>

       char *tmpnam(char *s);
       char *tmpnam_r(char *s);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

           Since glibc 2.19:
           Up to and including glibc 2.19:
               _BSD_SOURCE || _SVID_SOURCE

       Note:  avoid  using  these  functions;  use  mkstemp(3)  or  tmpfile(3)

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

       The tmpnam_r() function performs the same task as tmpnam(), but returns
       NULL (to indicate an error) if s is NULL.

       These functions return a pointer to a  unique  temporary  filename,  or
       NULL if a unique name cannot be generated.

       No errors are defined.

       For   an   explanation   of   the  terms  used  in  this  section,  see

       |Interface  | Attribute     | Value                    |
       |tmpnam()   | Thread safety | MT-Unsafe race:tmpnam/!s |
       |tmpnam_r() | Thread safety | MT-Safe                  |
       tmpnam(): SVr4, 4.3BSD, C89,  C99,  POSIX.1-2001.   POSIX.1-2008  marks
       tmpnam() as obsolete.

       tmpnam_r()  is  a nonstandard extension that is also available on a few
       other systems.

       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 these functions generate names that are difficult to guess, it
       is  nevertheless  possible  that  between the time that the pathname is
       returned 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

       Never use these functions.  Use mkstemp(3) or tmpfile(3) instead.

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

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                                  2017-09-15                         TMPNAM(3)
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