TMPNAM(3S)          UNIX Programmer's Manual           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;

HP-UX COMPATIBILITY
     Level:    HP-UX/NUCLEUS

     Origin:   System V

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

     _T_m_p_n_a_m always generates a file name using the path-prefix
     defined as P_tmpdir in the <_s_t_d_i_o._h> header file.  If _s is
     NULL, _t_m_p_n_a_m leaves its result in an internal static area
     and returns a pointer to that area.  The next call to _t_m_p_n_a_m
     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
     <_s_t_d_i_o._h>; _t_m_p_n_a_m places its result in that array and
     returns _s.  _T_e_m_p_n_a_m allows the user to control the choice of
     a directory.  The argument _d_i_r points to the name of the
     directory in which the file is to be created.  If _d_i_r is
     NULL or points to a string which is not a name for an
     appropriate directory, the path-prefix defined as P_tmpdir
     in the <_s_t_d_i_o._h> header file is used.  If that directory 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
     the name of the desired temporary-file directory.  Many
     applications prefer their temporary files to have certain
     favorite initial letter sequences in their names.  Use the
     _p_f_x 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.  _T_e_m_p_n_a_m uses
     _m_a_l_l_o_c(3C) to get space for the constructed file name, and
     returns a pointer to this area.  Thus, any pointer value
     returned from _t_e_m_p_n_a_m may serve as an argument to _f_r_e_e (see
     _m_a_l_l_o_c(3C)).  If _t_e_m_p_n_a_m cannot return the expected result
     for any reason, i.e.  _m_a_l_l_o_c(3C) failed, or none of the
     above mentioned attempts to find an appropriate directory
     was successful, a NULL pointer will be returned.

NOTES
     These functions generate a different file name each time
     they are called.  Files created using these functions and
     either _f_o_p_e_n(3S) or _c_r_e_a_t(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 _u_n_l_i_n_k(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, 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 _m_k_t_e_m_p, and the
     file names are chosen so as to render duplication by other
     means unlikely.