


      TMPNAM(3S)                  (UNIX 5.0)                 TMPNAM(3S)



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

      SYNTAX
           #include <stdio.h>

           char *tmpnam (s)
           char *s;

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

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

           Tmpnam always generates a file name using the path-name
           defined as P_tmpdir 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
           L_tmpnam bytes, where L_tmpnam 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 path-name of the
           directory in which the file is to be created.  If dir is
           NULL or points to a string which is not a path-name for an
           appropriate directory, the path-name defined as P_tmpdir in
           the <stdio.h> header file is used.  If that path-name is not
           accessible, /tmp will be used as a last resort.  This entire
           sequence can be up-staged by providing an environment
           variable TMPDIR in the user's environment, whose value is a
           path-name for the desired temporary-file directory.

           Many applications prefer their temporary files to have
           certain favorite initial letter sequences in their names.
           Use the pfx argument for this.  This argument may be NULL or
           point to a string of up to five characters to be used as the
           first few characters of the temporary-file name.

           Tempnam uses malloc(3C) to get space for the constructed
           file name, 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 none
           of the above mentioned attempts to find an appropriate
           directory was successful, a NULL pointer will be returned.

      NOTES



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      TMPNAM(3S)                  (UNIX 5.0)                 TMPNAM(3S)



           These functions generate a different file name each time
           they are called.

           Files created using these functions and either fopen or
           creat 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), malloc(3C), mktemp(3C), tmpfile(3S).

      BUGS
           If called more than 17,576 times in a single process, these
           functions will start recycling previously used names.
           Between the time a file name 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 these functions or mktemp, and the
           file names are chosen so as to render duplication by other
           means unlikely.


































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