pts(4) - man - phpMan

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



NAME
       ptmx, pts - pseudoterminal master and slave

DESCRIPTION
       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  ob‐
       tained  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
       /dev/ptmx, /dev/pts/*

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

COLOPHON
       This  page  is  part  of  release  5.10 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)