UUCP /etc/uucp/Devices File
The /etc/uucp/Devices file contains information for all the devices that can be used to
establish a link to a remote computer. These devices include ACUs (which include high-speed
modems), direct links, and network connections.
An entry in the /etc/uucp/Devices file has the following syntax:
Type Line Line2 Class Dialer-Token-Pairs
The following is an entry in the Devices file for a U.S. Robotics V.32bis
modem that is attached to port A and is running at 38,400 bps.
ACUEC cua/a - 38400 usrv32bis-ec
Entry in the Type field. For more information, see Type Field in /etc/uucp/Devices File.
Entry in the Line field. For more information, see Line Field in the /etc/uucp/Devices File.
Entry in the Line2 field. For more information, see Line2 Field in the /etc/uucp/Devices File.
Entry in the Class field. For more information, see Class Field in the /etc/uucp/Devices File.
Entry in the Dialer-Token-Pairs field. For more information, see Dialer-Token-Pairs Field in the /etc/uucp/Devices File.
Each field is described in the next section.
Type Field in /etc/uucp/Devices File
This field describes the type of link that the device establishes. The UUCP Type
field can contain one of the keywords that is described in the sections that
The Direct keyword appears mainly in entries for cu connections. This keyword indicates that
the link is a direct link to another computer or a port selector. Create
a separate entry for each line that you want to reference through the -l
option of cu.
The ACU keyword indicates that the link to a remote computer (whether through cu, UUCP,
asppp, or Solaris PPP 4.0) is made through a modem. This modem can be
connected either directly to your computer or indirectly through a port selector.
The port selector is a variable that is replaced in the Type field by
the name of a port selector. Port selectors are devices that are attached to
a network that prompts for the name of a calling modem, then grant access.
The file /etc/uucp/Dialers contains caller scripts only for the micom and develcon port
selectors. You can add your own port selector entries to the Dialers file. See UUCP /etc/uucp/Dialers File
for more information.
This variable is replaced by the name of a machine in the Type field,
indicating that the link is a direct link to this particular computer. This naming
scheme is used to associate the line in this Devices entry with an entry
in /etc/uucp/Systems for the computer System-Name.
Type Fields in Devices File and Systems File
Example 26-5 shows a comparison of the fields in /etc/uucp/Devices and the fields in /etc/uucp/Systems.
The keyword that is used in the Type field of the Devices file
is matched against the third field of the Systems file entries. In the Devices
file, the Type field has the entry ACUEC, indicating an automatic call unit, in this
instance a V.32bis modem. This value is matched against the Type field in the
Systems file, which also contains the entry ACUEC. See UUCP /etc/uucp/Systems File for more information.
Example 26-5 Comparison of Type Fields in Devices
file and Systems
The following is an example of an entry in the Devices file.
ACUEC cua/a - 38400 usrv32bis-ec
The following is an example of an entry in the Systems file.
Arabian Any ACUEC 38400 111222 ogin: Puucp ssword:beledi
Line Field in the /etc/uucp/Devices File
This field contains the device name of the line (known as port) that is
associated with the Devices entry. If the modem that is associated with a
particular entry were attached to the /dev/cua/a device (serial port A), the name that
is entered in this field would be cua/a. An optional modem control flag, M,
can be used in the Line field to indicate that the device should be
opened without waiting for a carrier. For example:
Line2 Field in the /etc/uucp/Devices File
This field is a placeholder. Always use a hyphen (-) here. 801–type dialers, which are
not supported in the Solaris OS, use the Line2 field. Non-801 dialers do not
normally use this configuration, but still require a hyphen in this field.
Class Field in the /etc/uucp/Devices File
The Class field contains the speed of the device, if the keyword ACU
or Direct is used in the Type field. However, the Class field can contain
a letter and a speed, such as C1200 or D1200, to differentiate between
classes of dialers, such as Centrex or Dimension PBX.
This differentiation is necessary because many larger offices can have more than one type
of telephone network. One network might be dedicated to serving only internal office communications while
another network handles the external communications. In such a situation, you must distinguish which line
or lines should be used for internal communications and which should be used for
The keyword that is used in the Class field of the Devices file
is matched against the Speed field of the Systems file.
Example 26-6 Class Field in the Devices
ACU cua/a - D2400 hayes
Some devices can be used at any speed, so the keyword Any can be
used in the Class field. If Any is used, the line matches any
speed that is requested in the Speed field of the Systems file. If this
field is Any and the Systems file Speed field is Any, the speed defaults to
Dialer-Token-Pairs Field in the /etc/uucp/Devices File
The Dialer-Token-Pairs (DTP) field contains the name of a dialer and the token to
pass it. The DTP field has this syntax:
dialer token [dialer token]
The dialer portion can be the name of a modem, a port monitor, or
it can be direct or uudirect for a direct-link device. You can have
any number of dialer-token pairs. If the dialer portion is not present, it is
taken from a related entry in the Systems file. The token portion can be supplied
immediately after the dialer portion.
The last dialer-token pair might not be present, depending on the associated dialer. In
most situations, the last pair contains only a dialer portion. The token portion is retrieved
from the Phone field of the associated Systems file entry.
A valid entry in the dialer portion can be defined in the Dialers
file or can be one of several special dialer types. These special dialer types are
compiled into the software and are therefore available without having entries in the Dialers
file. The following list shows the special dialer types.
Transport Level Interface Network (without STREAMS)
Transport Level Interface Network (with STREAMS)
See Protocol Definitions in /etc/uucp/Devices File for more information.
Structure of the Dialer-Token-Pairs Field in the /etc/uucp/Devices File
The DTP field can be structured four different ways, depending on the device that
is associated with the entry.
See the first way that the DTP field can be structured:
Directly connected modem – If a modem is connected directly to a port on your computer,
the DTP field of the associated Devices file entry has only one pair. This
pair would normally be the name of the modem. This name is used to
match the particular Devices file entry with an entry in the Dialers file. Therefore,
the Dialer field must match the first field of a Dialers file entry.
Example 26-7 Dialers Field for Directly Connect Modem
Dialers hayes =,-, "" \\dA\pTE1V1X1Q0S2=255S12=255\r\c
Notice that only the dialer portion (hayes) is present in the DTP field of
the Devices file entry. This means that the token to be passed on to
the dialer (in this instance, the phone number) is taken from the Phone field
of a Systems file entry. (\T is implied, as described in Example 26-9.)
See the second and third ways that the DTP field can be structured:
Direct link – For a direct link to a particular computer, the DTP field of the associated entry would contain the keyword direct. This condition is true for both types of direct-link entries, Direct and System-Name. Refer to Type Field in /etc/uucp/Devices File.
Computers on the same port selector – If a computer with which you intend to communicate is on the same port selector switch as your computer, your computer must first access the switch. The switch then makes the connection to the other computer. This type of entry has only one pair. The dialer portion is used to match a Dialers file entry.
Example 26-8 UUCP Dialers Field for Computers on Same Port Selector
Dialers develcon ,"" "" \pr\ps\c est:\007 \E\D\e \007
As shown, the token portion is left blank. This designation indicates that it is
retrieved from the Systems file. The Systems file entry for this computer contains the token
in the Phone field, which is normally reserved for the phone number of the
computer. Refer to UUCP /etc/uucp/Systems File for details. This type of DTP contains an escape
character (\D), which ensures that the content of the Phone field is not interpreted as
a valid entry in the Dialcodes file.
See the fourth way that the DTP field can be structured:
Modems that are connected to port selector – If a high-speed modem is connected to a port selector, your computer must
first access the port selector switch. The switch makes the connection to the modem.
This type of entry requires two dialer-token-pairs. The dialer portion of each pair
(the fifth and seventh fields of the entry) is used to match entries in
the Dialers file, as follows.
Example 26-9 UUCP Dialers Field for Modems Connected to Port Selector
develcon "" "" \pr\ps\c est:\007 \E\D\e \007
ventel =&-% t"" \r\p\r\c $ <K\T%\r>\c ONLINE!
In the first pair, develcon is the dialer and vent is the
token that is passed to the Develcon switch to tell it which device, such
as a Ventel modem, to connect to your computer. This token is unique for
each port selector, as each switch can be set up differently. After the Ventel
modem has been connected, the second pair is accessed. Ventel is the dialer and
the token is retrieved from the Systems file.
Two escape characters can appear in a DTP field:
\T – Indicates that the Phone (token) field should be translated by using the /etc/uucp/Dialcodes file. This escape character is normally placed in the /etc/uucp/Dialers file for each caller script that is associated with a modem, such as Hayes, and U.S. Robotics. Therefore, the translation does not occur until the caller script is accessed.
\D – Indicates that the Phone (token) field should not be translated by using the /etc/uucp/Dialcodes file. If no escape character is specified at the end of a Devices entry, the \D is assumed (default). A \D is also used in the /etc/uucp/Dialers file with entries that are associated with network switches develcon and micom.
Protocol Definitions in /etc/uucp/Devices File
You can define the protocol to use with each device in /etc/uucp/Devices. This
specification is usually unnecessary because you can use the default or define the protocol with
the particular system you are calling. Refer to UUCP /etc/uucp/Systems File for details. If you
do specify the protocol, you must use the following form:
For example, you can use TCP,te to specify the TCP/IP protocol.
The following table shows the available protocols for the Devices file.
Table 26-2 Protocols Used in /etc/uucp/Devices
protocol is commonly used for transmissions over TCP/IP and other reliable connections. t assumes error-free
This protocol is UUCP's native protocol. g is slow, reliable, and good
for transmission over noisy telephone lines.
This protocol assumes transmission over error-free channels
that are message oriented, as opposed to byte-stream oriented, such as TCP/IP.
protocol is used for transmission over X.25 connections. f relies on flow control of
the data stream and is meant for working over links that can (almost) be
guaranteed to be error free, specifically X.25/PAD links. A checksum is enacted over a whole
file only. If a transport fails, the receiver can request retransmission or retransmissions.
Here is an example that shows a protocol designation for a device entry:
TCP,te - - Any TCP -
This example indicates that, for device TCP, you should try to use the t
protocol. If the other end of the transmission refuses, use the e protocol.
Neither e nor t is appropriate for use over modems. Even if
the modem assures error-free transmission, data can still be dropped between the modem and the