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);
       char *tmpnam_r(char *s);

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

       tmpnam_r()
           Since glibc 2.19:
               _DEFAULT_SOURCE
           Up to and including glibc 2.19:
               _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION

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

       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  men-
       tioned below.)

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

RETURN VALUE

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

ERRORS

       No errors are defined.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       +-----------+---------------+--------------------------+
       |Interface  | Attribute     | Value                    |
       +-----------+---------------+--------------------------+
       |tmpnam()   | Thread safety | MT-Unsafe race:tmpnam/!s |
       +-----------+---------------+--------------------------+
       |tmpnam_r() | Thread safety | MT-Safe                  |
       +-----------+---------------+--------------------------+
CONFORMING TO

       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.

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 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 defined.

BUGS

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

SEE ALSO

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

COLOPHON

       This page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and  the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

                                                                    2017-09-15                                                           TMPNAM(3)