tmpnam(3S)                                             tmpnam(3S)



     NAME
          tmpnam, tempnam - create a name for a temporary file

     SYNOPSIS
          #include <stdio.h>

          char *tmpnam (s)
          char *s;

          char *tempnam (dir, pfx)
          char *dir, *pfx;

     DESCRIPTION
          These functions generate filenames that can safely be used
          for a temporary file.

          tmpnam always generates a filename using the pathname
          defined as ptmpdir in the <stdio.h> header file.  If s is
          NULL, tmpnam leaves its result in an internal static area
          and returns a pointer to that area.  The next call to tmpnam
          will destroy the contents of the area.  If s is not NULL, it
          is assumed to be the address of an array of at least
          ltmpnam bytes, where ltmpnam is a constant defined in
          <stdio.h>; tmpnam places its result in that array and
          returns s.

          tempnam allows the user to control the choice of a
          directory.  The argument dir points to the pathname of the
          directory in which the file is to be created.  If dir is
          NULL or points to a string which is not a pathname for an
          appropriate directory, the pathname defined as ptmpdir in
          the <stdio.h> header file is used.  If that pathname is not
          accessible, /tmp will be used as a last resort.  This entire
          sequence can be upstaged by providing an environment
          variable TMPDIR in the user's environment, whose value is a
          pathname for the desired temporary-file directory.

          Many applications prefer that names of temporary files
          contain favorite initial letter sequences.  Use the pfx
          argument for this.  This argument may be NULL or point to a
          string of up to 5 characters to be used as the first few
          characters of the name of the temporary file.

          tempnam uses malloc(3C) to get space for the constructed
          filename and returns a pointer to this area.  Thus, any
          pointer value returned from tempnam may serve as an argument
          to free (see malloc(3C)).  If tempnam cannot return the
          expected result for any reason (i.e., malloc failed or
          attempts to find an appropriate directory were
          unsuccessful), a NULL pointer will be returned.

     NOTES



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     tmpnam(3S)                                             tmpnam(3S)



          These functions generate a different filename each time they
          are called.

          Files created using these functions and either fopen(3S) or
          creat(2) are temporary only in the sense that they reside in
          a directory intended for temporary use and their names are
          unique.  It is the user's responsibility to use unlink(2) to
          remove the file when its use is ended.

     SEE ALSO
          creat(2), unlink(2), fopen(3S), malloc(3C), mktemp(3C),
          tmpfile(3S).

     BUGS
          If called more than 17,576 times in a single process, tmpnam
          and tempnam will start recycling previously used names.
          Between the time a filename is created and the file is
          opened, it is possible for some other process to create a
          file with the same name.  This can never happen if that
          other process is using tmpnam, tempnam, or mktemp(3C) and
          the filenames are chosen carefully to avoid duplication by
          other means.

































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