tmpnam(3S)                                                       tmpnam(3S)

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

SYNOPSIS
     #include <stdio.h>

     char *tmpnam(char *s);

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

DESCRIPTION
     These functions generate filenames that can safely be used for a tem-
     porary file.

     tmpnam() always generates a filename using the path-prefix 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 choice of a directory to be controlled. The argu-
     ment dir points to the name of the directory in which the file is to
     be created. If dir is NULL or points to a string that is not a name
     for an appropriate directory, the path-prefix defined as Ptmpdir in
     the stdio.h header file is used. If that directory is not accessible
     via access(2), /tmp will be used as a last resort. This entire
     sequence can be improved by providing an environment variable TMPDIR,
     whose value is the name of the desired temporary-file directory.

     Many applications prefer their temporary files to have certain favor-
     ite 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
     bytes to be used as the first few bytes of the temporary filename.

     tempnam() uses malloc() 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 temp-
     nam() cannot return the expected result for any reason - e.g. malloc
     failed, or no appropriate directory could be found - a NULL pointer
     will be returned.

     tempnam() fails if there is not enough space.

NOTES
     These functions generate a different filename 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



Page 1                       Reliant UNIX 5.44                Printed 11/98

tmpnam(3S)                                                       tmpnam(3S)

     responsibility to remove the file when its use is ended. If called
     more than TMPMAX (defined in stdio.h) times in a single process,
     names which have been used previously will be reused.

     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 these functions
     or mktemp() and the filenames are chosen to render duplication by
     other means unlikely.

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









































Page 2                       Reliant UNIX 5.44                Printed 11/98