# phpman > info > pts

[PTS(4)](https://www.chedong.com/phpMan.php/man/PTS/4/markdown)                     Linux Programmer's Manual                    [PTS(4)](https://www.chedong.com/phpMan.php/man/PTS/4/markdown)

NAME
       ptmx, pts - pseudoterminal master and slave

DESCRIPTION
       The file /dev/ptmx (the pseudoterminal multiplexor device) is a charac-
       ter 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  pseu-
       doterminal  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)](https://www.chedong.com/phpMan.php/man/ptsname/3/markdown).

       Before opening the pseudoterminal slave, you  must  pass  the  master's
       file descriptor to [grantpt(3)](https://www.chedong.com/phpMan.php/man/grantpt/3/markdown) and [unlockpt(3)](https://www.chedong.com/phpMan.php/man/unlockpt/3/markdown).

       Once  both the pseudoterminal master and slave are open, the slave pro-
       vides 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  emula-
       tors  such as [xterm(1)](https://www.chedong.com/phpMan.php/man/xterm/1/markdown), in which data read from the pseudoterminal mas-
       ter 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)](https://www.chedong.com/phpMan.php/man/sshd/8/markdown), in which data read from the pseudoterminal  master  is
       sent across the network to a client program that is connected to a ter-
       minal or terminal emulator.

       Pseudoterminals can also be used to send input to  programs  that  nor-
       mally refuse to read input from pipes (such as [su(1)](https://www.chedong.com/phpMan.php/man/su/1/markdown), and [passwd(1)](https://www.chedong.com/phpMan.php/man/passwd/1/markdown)).

FILES
       /dev/ptmx, /dev/pts/*

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

SEE ALSO
       [getpt(3)](https://www.chedong.com/phpMan.php/man/getpt/3/markdown), [grantpt(3)](https://www.chedong.com/phpMan.php/man/grantpt/3/markdown), [ptsname(3)](https://www.chedong.com/phpMan.php/man/ptsname/3/markdown), [unlockpt(3)](https://www.chedong.com/phpMan.php/man/unlockpt/3/markdown), [pty(7)](https://www.chedong.com/phpMan.php/man/pty/7/markdown)

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)](https://www.chedong.com/phpMan.php/man/PTS/4/markdown)