• 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.
  
• 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,
  
  
  define
  
  
    _SVID_SOURCE or
  
  
    _BSD_SOURCE before including
  
  
    <stdio.h> .
  
   

• 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 3.19 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/.
  

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