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 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 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 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 5.13 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/.

                                            2021-03-22                                  TMPNAM(3)