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openpty(3)
NAME
  openpty, forkpty - Open and fork pseudoterminals

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 );

LIBRARY
  Standard C Library (libc)

PARAMETERS
  master
      Points to the returned file descriptor for the master pseudoterminal
      (pty).

  slave
      Points to the returned file descriptor for the slave pty.

  name
      Points to the pathname of the slave pty. This parameter is optional.

  termp
      Specifies the termios structure containing the terminal attributes for
      the opened slave pty. This parameter is optional.

  winp
      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
  specifications 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 unsuccessful, 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:

  [ENOENT]
      The slave pty special files have been exhausted.

  [ENXIO]
      No more ptys can be opened. The configured number of ptys has been
      reached.

  [EMFILE]
      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.

  [ENFILE]
      The system file table is full.

  [ENOMEM]
      The system was unable to allocate kernel memory for more file
      descriptors/processes.

  [EAGAIN]
      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.

SEE ALSO
  Functions: fork(2)

Index for Section 3

Alphabetical listing for O

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