November 12, 2005 PTM 4

### NAME

ptm - pseudo-terminal multiplexor device

### SYNOPSIS

pseudo-device pty[ count]

### 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-terminal 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[16];
              char    sn[16];
      };

  `

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 disabled 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 OpenBSD3.5 and was ported to NetBSD3.0.