CTERMID(3S)         UNIX Programmer's Manual          CTERMID(3S)

NAME
     ctermid - generate file name for terminal

SYNOPSIS
     #include <stdio.h>

     char *ctermid(s)
     char *s;

HP-UX COMPATIBILITY
     Level:    HP-UX/RUN ONLY

     Origin:   System III

DESCRIPTION
     _C_t_e_r_m_i_d generates a string that refers  to  the  controlling
     terminal for the current process when used as a file name.

     If (int)_s is zero, the  string  is  stored  in  an  internal
     static  area,  the  contents of which are overwritten at the
     next call to _c_t_e_r_m_i_d, and the address of which is  returned.
     If (int)_s is non-zero, then _s is assumed to point to a char-
     acter array of at least L_ctermid elements;  the  string  is
     placed  in  this  array and the value of _s is returned.  The
     manifest constant L_ctermid is defined in <stdio.h>.

     The difference  between  _c_t_e_r_m_i_d  and  _t_t_y_n_a_m_e(3C)  is  that
     _t_t_y_n_a_m_e  must  be  handed  a file descriptor and returns the
     actual name  of  the  terminal  associated  with  that  file
     descriptor,  while _c_t_e_r_m_i_d returns a magic string (/dev/tty)
     that will refer to the terminal if  used  as  a  file  name.
     Thus  _t_t_y_n_a_m_e  is  useless unless the process already has at
     least one file open to a terminal.

SEE ALSO
     ttyname(3C).