System Administration Guide
Chapter 7, Connecting to other computers with UUCP

Specifying dial-up parameters with the Devices file

Specifying dial-up parameters with the Devices file

The Devices file (/usr/lib/uucp/Devices) contains information for all the devices that can be used to establish a link to a remote computer. Devices are Automatic Call Units, direct links, or network connections. This file works closely with the Dialers, Systems, and Dialcodes files. Before you make changes in any of these files, you should be familiar with them all. A change to an entry in one file may require a change to a related entry in another file.

Each entry in the Devices file has the following format: 

type ttyline dialerline speed dialer-token

where:

type
contains one of two keywords (Direct or ACU), the name of a Local Area Network switch, or a system name. 

ttyline
contains the device name of the port associated with the Devices entry. For example, if the automatic dial modem for a particular entry was attached to the /dev/tty1A line, the name entered in this field would be ``tty1A''.

dialerline
is useful only for 801-type dialers, which do not contain a modem and must use an additional line. Unless you have an 801 dialer, simply enter a hyphen (-) as a placeholder.

speed
is the speed or speed range of the device. Can also contain an indicator for distinguishing different dialer classes.

dialer-token
contains pairs of dialers and tokens, each representing a dialer and an argument to be passed to it. The dialer portion can be the name of a binary dialer program, a Dialers file entry, or Direct for a direct link device.

The type field

This field usually contains one of two keywords (Direct or ACU) the name of a Local Area Network switch, or a system name. 

Direct
indicates a direct link to another computer or a switch for cu connections.



ACU
indicates that the link to a remote computer is made through an Automatic Call Unit. This modem can be connected either directly to your computer or indirectly through a Local Area Network (LAN) switch. 

LANswitch
can be replaced by the name of a LAN switch. micom and develcon are supplied with caller scripts in the Dialers file. You can add your own LAN switch entries to the Dialers file. If you are adding a network using TCP/IP you would use the special dialer types TCP, TLI, or TLIS. See ``Configuring UUCP over TCP/IP'' in the Networking Guide.

sysname
indicates a direct link to a particular computer. (sysname is replaced by the name of the computer.) This means that the line associated with this Devices entry is for a particular computer in the Systems file.

For example, the keyword gorgon used in the type field of the Devices file is matched against the third field of the Systems file entry:

Devices: gorgon tty1a - 1200 direct

Systems: gorgon Any gorgon 1200 - ogin: nuucp ssword: DontLook

You can designate a protocol to use for a device within this field. For more information, see ``Defining a communications protocol''.


NOTE: Although the use of a system name adds clarity, only defined tokens can be used.



The speed field

In most cases, this is simply the speed of the device, if the keyword ACU or Direct is used in the type field. However, speed can contain a letter and a speed (for example, C1200, D1200) to differentiate between classes of dialers (Centrex or Dimension PBX). This is necessary because many larger offices may have more than one type of telephone network: one network may be dedicated to serving only internal office communications, while another handles the external communications. It is necessary to distinguish which lines are used for internal communications and which are used for external communications. The keyword used in the speed field of the Devices file is matched against the fourth field of the Systems file entries, for example:

Devices: ACU tty1A - D1200 hayes1200

Systems: gorgon Any ACU D1200 3251 ogin: nuucp ssword: DontLook

Some devices can be used at any speed, so the keyword Any can be used in the speed field. If Any is used, the line matches any speed requested in a Systems file entry. If this field is Any and the Systems file speed field is Any, the speed defaults to 1200bps. If a device can be used at a range of speeds, then the speed field can specify this range (for example, 1200--9600 or D1200--9600). This is preferable to the use of Any.

The dialer-token field

This field has the following format:

dialer [ token dialer token ... ]

For a direct line, this field contains simply the word direct, and no token is required.

For a simple connection to a dialer, this field contains the name of the dialer, and the token is omitted; by default it is taken from the phone number field of the Systems file entry.

For a dialer or a network dataswitch, this field contains the name of an entry found in the Dialers file (develcon and micom are examples of network data switches). Other dialer types are supported by binaries instead of Dialers entries. (Support for 801-type dialers is provided through use of separate lines for data and the dialer. See the Devices file for details.) UUCP recognizes a dialer as a binary if the name begins with a ``/'' or if there is an executable file by that name in /usr/lib/uucp.

For more information on Dialers entries and binaries, see ``Using dialers'' in the SCO OpenServer Handbook.

Structuring dialer-token entries

The dialer-token can be structured four different ways, depending on the device associated with the entry: 

Here are two escape characters that can appear in the dialer-token field: 

\T
indicates that the Phone field should be translated at this stage, using the Dialcodes file. This escape character is normally placed in the Dialers file for each caller script associated with an automatic dial modem (penril, ventel, and so on). The translation does not take place until the caller script is accessed.

\D
indicates that the Phone field should not be translated using the Dialcodes file. If no escape character is specified at the end of a Devices entry, ``\D'' is assumed by default when a Dialers script is to be used (which can itself contain a ``\T'' to translate the number). ``\T'' is assumed if a built-in or dialer binary is to be used (because there is then no later opportunity to translate the number).