ptm(4) - NetBSD Manual Pages

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PTM(4)                  NetBSD Kernel Interfaces Manual                 PTM(4)


NAME

     ptm -- pseudo-terminal multiplexor device


SYNOPSIS

     pseudo-device pty


DESCRIPTION

     The ptm driver is the backend for the /dev/ptm device.  It supports three
     ioctl(2)s.  The first is TIOCPTMGET, which allocates a free pseudo-termi-
     nal device, sets its user ID to the calling user, revoke(2)s it, and
     returns the opened file descriptors for both the master and the slave
     pseudo-terminal device to the caller in a struct ptmget.  This struct has
     the following content:

           struct ptmget {
                   int     cfd;
                   int     sfd;
                   char    cn[PATH_MAX];
                   char    sn[PATH_MAX];
           };

     where cfd and sfd contain the master resp. slave device's file descriptor
     and cn and sn the corresponding paths in the file system.

     The /dev/ptmx device supports two more ioctl(2)s, TIOCGRANTPT, which is
     used by grantpt(3), TIOCPTSNAME, which is used by ptsname(3).

     The ptm device is included with the pseudo-device pty(4).  It can be dis-
     abled by adding ``options NO_DEV_PTM'' to the kernel configuration.


FILES

     /dev/ptm                          ptm access device

     /dev/ptmx                         ptm cloning device, used to implement
                                       Unix98 ptys


SEE ALSO

     grantpt(3), openpty(3), posix_openpt(3), ptsname(3), unlockpt(3), pty(4)


HISTORY

     The /dev/ptm device appeared in OpenBSD 3.5 and was ported to NetBSD 3.0.

NetBSD 9.3                     November 30, 2013                    NetBSD 9.3