pts(4) — Linux manual page

NAME | DESCRIPTION | FILES | NOTES | SEE ALSO | COLOPHON

PTS(4)                  Linux Programmer's Manual                 PTS(4)

NAME         top

       ptmx, pts - pseudoterminal master and slave

DESCRIPTION         top

       The file /dev/ptmx (the pseudoterminal multiplexor device) is a
       character file with major number 5 and minor number 2, usually
       with mode 0666 and ownership root:root.  It is used to create a
       pseudoterminal master and slave pair.

       When a process opens /dev/ptmx, it gets a file descriptor for a
       pseudoterminal master and a pseudoterminal slave device is
       created in the /dev/pts directory.  Each file descriptor obtained
       by opening /dev/ptmx is an independent pseudoterminal master with
       its own associated slave, whose path can be found by passing the
       file descriptor to ptsname(3).

       Before opening the pseudoterminal slave, you must pass the
       master's file descriptor to grantpt(3) and unlockpt(3).

       Once both the pseudoterminal master and slave are open, the slave
       provides processes with an interface that is identical to that of
       a real terminal.

       Data written to the slave is presented on the master file
       descriptor as input.  Data written to the master is presented to
       the slave as input.

       In practice, pseudoterminals are used for implementing terminal
       emulators such as xterm(1), in which data read from the
       pseudoterminal master is interpreted by the application in the
       same way a real terminal would interpret the data, and for
       implementing remote-login programs such as sshd(8), in which data
       read from the pseudoterminal master is sent across the network to
       a client program that is connected to a terminal or terminal
       emulator.

       Pseudoterminals can also be used to send input to programs that
       normally refuse to read input from pipes (such as su(1), and
       passwd(1)).

FILES         top

       /dev/ptmx, /dev/pts/*

NOTES         top

       The Linux support for the above (known as UNIX 98 pseudoterminal
       naming) is done using the devpts filesystem, which should be
       mounted on /dev/pts.

SEE ALSO         top

       getpt(3), grantpt(3), ptsname(3), unlockpt(3), pty(7)

COLOPHON         top

       This page is part of release 5.11 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                          2020-08-13                         PTS(4)

Pages that refer to this page: getpt(3)grantpt(3)posix_openpt(3)ptsname(3)ttyname(3)unlockpt(3)proc(5)pty(7)