tmpnam

 NAME
  tmpnam - create a unique, temporary file name

 SYNOPSIS
  #include <stdio.h>

  char *filename = tmpnam(buf);
  char *buf;

 FUNCTION
  tmpnam() creates a unique temporary file name meant to never
  be seen by the user.  The filename tmpnam() creates will be
  no more than L_tmpnam bytes long (L_tmpnam is a macro in <stdio.h>),
  including the nul so you can simply declare a buffer:

      char buf[L_tmpnam];

  tmpnam() returns the buffer into which it created the temporary
  file name.  If you specify a non-NULL buffer it returns its first
  argument.

  If you pass NULL to tmpnam() then tmpnam() will use its down internal
  static buffer (overwritting any previous name that was stored in
  said buffer) and return a pointer to that.

 EXAMPLE
  #include <stdio.h>
  #include <assert.h>

  main()
  {
      char buf[L_tmpnam];
      char *ptr;

      ptr = tmpnam(NULL);
      puts(ptr);

      assert(tmpnam(buf) == buf);     /*  returns argument */
      puts(buf);

                      /*  haven't overwritten it yet */
      printf("%s (same as first)n", ptr);

      assert(tmpnam(NULL) == ptr);    /*  that will overwrite it!    */
      puts(ptr);

      return(0);
  }

 INPUTS
  char *buf;      optional buffer of at least L_tmpnam bytes to
              hold the temporary file name or NULL to have
              tmpnam() use its own internal buffer.

 RESULTS
  char *ptr;      pointer to buffer (buf if buf != NULL)

 SEE ALSO
  tmpfile