openpty(3)						     Library Functions Manual							openpty(3)

NAME

       openpty, forkpty - Open and fork pseudoterminals

LIBRARY

       Standard C Library (libc.a)

SYNOPSIS

       #include <sys/termios.h>
		<sys/ioctl.h>
       int openpty(	 int *master,	   int *slave,	    char *name,      struct termios *termp,	 struct winsize *winp);
       pid_t  forkpty(	    int *master,      char *name,      struct termios *termp,	   struct winsize *winp);

PARAMETERS

       Points  to  the	returned  file	descriptor for the master pseudoterminal (pty).  Points to the returned file descriptor for the slave pty.
       Points to the pathname of the slave pty.  This parameter is optional.  Specifies the termios structure containing the  terminal	attributes
       for  the  opened  slave	pty.  This parameter is optional.  Specifies the winsize structure containing the window attributes for the opened
       slave pty.  This parameter is optional.

DESCRIPTION

       The openpty() function opens the pty master/slave pair and sets the terminal attributes of the slave pseudoterminal according to the speci-
       fications  in  the  termp  and  winp parameters.  The forkpty() function creates a child process and establishes the slave pty as the child
       process' controlling terminal.  The openpty() function will first attempt to open an SVR4 slave device, such as /dev/pts/11.  If unsuccess-
       ful, it will attempt a BSD device, such as /dev/ttyp1.

									  Note
	    If	a  signal  handler  for SIGCHLD exists and the openpty() or forkpty() function is invoked without superuser privileges, the signal
	    handler must be able to dismiss an unexpected SIGCHLD signal.

RETURN VALUES

       Upon successful completion, the openpty() function returns a value of 0 (zero).	Otherwise, it returns a value of -1.

       On success, the forkpty() function returns a value of 0 (zero) to the child process and returns the process ID of the child process to  the
       parent process.	On error, the forkpty() function returns a value of -1 to the parent process and does not create a child process.

ERRORS

       If  any	of the following conditions occurs, the openpty() function sets errno to the corresponding value: The slave pty special files have
       been exhausted.	No more ptys can be opened.  The configured number of ptys has been reached.  The system limit for open  file  descriptors
       per process has already reached OPEN_MAX.  The system limit for open file descriptors has been reached.

	      [Tru64  UNIX]  Either  the  OPEN_MAX value or the per-process soft descriptor limit is checked.  The system file table is full.  The
	      system was unable to allocate kernel memory for more file descriptors/processes.	The system-imposed limit on the  total	number	of
	      processes executing for a single user has been exceeded.	This limit can be exceeded by a process with superuser privilege.

RELATED INFORMATION

       Functions: fork(2) delim off

																	openpty(3)