Man page of Systems
Section: Devices and Network Interfaces (4)
Return to Main Contents
Systems - Contains information about remote systems that can be contacted using the uucp program.
The /usr/lib/uucp/Systems file contains an entry for each
remote system that the local system can communicate with using uucp.
The uucp program cannot establish a connection with a remote system
unless it has an entry in the Systems file. The Systems files must
be configured on each system running the uucp program.
Note that only someone with root user authority can edit
the Systems file, which is owned by the uucp login ID.
Fields in the Systems File
The Systems file should contain a description of each system that
the local system can establish a remote connection with.
Each line in the Systems file includes the following fields:
sys_name Time Caller Class Phone Login
The name of the remote system. In general, names should be a
maximum of seven characters in length and must be unique. To
insure compatibility with some older systems, names should only
include lowercase characters and digits.
There can be more than one entry for each sys_name. Each
additional entry for a specific system represents an additional
communications path that uucp will sequentially try if
communication cannot be established using an earlier entry.
Specifies the times when the local system can call the remote
system. This field consists of three subfields: day, for
the day of the week (required), time, for the time of the day when the
system can call (optional), and retry, for
the minimum retry period in minutes (optional). The day and
time subfields are not separated with spaces. The retry field
is separated by a semicolon.
The day subfield is specified using the following keywords:
system can call on any day
system can never call the remote system. The
remote system will have to call the local system.
any weekday. You can also use Mo, Tu, We, Th,
Fr, and Sa, for example MoWeFr, for Monday,
Wednesday, and Friday.
The day subfield is required, unlike the time
and retry fields.
The time subfield is specified contains two times, in 24-hour
clock notation, which specify a range of times. Leave this
subfield blank if the remote system can be called at any time
during the day. For example, if a remote system can only be
called during the morning, enter 0800-1200 in the subfield.
The time subfield can also specify when the remote system cannot
be reached if the time range entered spans 0000. For example,
0800-0600 means the remote system can be contacted at any time,
except between 6:00 am and 8:00 am.
Multiple time fields can be included by using a comma as a
separator. For example, WK1800-0600,Sa,Su means the remote
system can be contacted at any time on a week day except between
6:00 pm. and 6:00 am, and at any time on Saturday and Sunday.
The optional retry subfield, specifies the minimum
time, in minutes, before uucp can try again to contact a remote system
after an unsuccessful attempt.
This subfield is separated from the rest of the string
by a semicolon. For example, Any0800-1200;3 specifies that
3 minutes is the minimum period after which uucico can try this
system again once it has been invoked explicitly or by the cron
daemon. Usually, uucp will attempt to contact the remote system
twice and if uucp fails, it will exit. The uucp command
can be invoked again after the 3 minute period.
Specifies the type of connection to be used to communicate with
the remote system. Use the ACU keyword for a telephone connection
using a modem or TCP (for a connection using TCP/IP).
Alternatively, sys_name can be used for a hardwired connection.
If TCP is used, there is a subfield which specifies a conversion
protocol. The default is the g protocol. Other protocols are
e, f, and t which are faster and more efficient
than the g protocol. To specify a particular protocol,
place a comma and the protocol letter after TCP, for
The entry specified in this field must have a corresponding
entry in the /usr/lib/uucp/Devices file.
The speed in bits per second for the device. Unless it is
necessary to use a specific baud rate, use the keyword Any.
This instructs uucp to match a speed that is appropriate for the
ACU of system connection specified in the Caller field.
For a telephone connection, the rate you enter in this field
should correspond to a rate specified in the Class field of an
entry in the /usr/lib/uucp/Devices file.
For a TCP connection, do not specify a baud rate. Instead, use
a hyphen, -, as a placeholder.
The phone number used to reach the remote system. For a hardwired
or TCP connection, use a hyphen, -, as a placeholder.
The phone number can be the complete phone number of the remote
system or a combination of an alphabetic abbreviation that
represents the dialing prefix and the remainder of the
number; see Dialcodes(4).
An equal sign, =, in the phone number indicates a wait for a secondary
dial tone. This may be required when a special number sequence must
be used to access an outside line, for example. For modems
that do not have the ability to detect a secondary dial tone,
the = sign generates a pause instead. A hyphen, -, in
the phone number generates a 1-second pause.
The ``chat string'' which describes the initial conversation
between systems to complete the login procedure. The string
consists of ``expect-send'' pairs (separated by spaces) and
optional ``subexpect-subsend'' pairs (separated by hyphens).
The ``expect'' portion contains characters that the local system
expects to receive from the remote system. The ``send'' portion
contains a string of characters that are sent to the remote
system upon receipt of the ``expect'' string. For example, the
first expect string generally contains the remote system's
login prompt, and the first send string generally contains the
login ID to be used on the remote system. The second expect
string contains the remote password prompt and the second send
string contains the remote system's password. For example,
in: uucp word: sysuucp
Note that the expect portion in the example contained only the
trailing part of the full strings expected, login:
and password:, respectively. The expect string
only needs to contain part of what is expected. This helps to
avoid problems with remote
systems that may use Login: or Password: instead
of login: and password:.
The use of ``subexpect-subsend'' strings is shown below:
in:--in: uucp word: sysuucp
In the example, the local system expects to receive the string
in:. If the local system gets that string, uucp goes on to
the next field in the ``expect-send'' sequence, which is uucp.
However, if the local system does not get that string, it sends
its own string, which is enclosed by hyphens after the expect
string. In the above example, a null character followed by a
newline is sent. The local system then expects the in:
(the second instance of it in the example). The newline sent
to the remote generally causes it to respond with its login
prompt, and the login ID can be sent followed by password processing.
The following strings can be included in the Login field:
Suppress the newline at the end of the send string
Delay two seconds before sending or reading more characters
Pause for approximately .25 to .50 seconds
Turn on the echo check (useful in Dialers file)
Turn off the echo check (useful in Dialers file)
Send a BREAK character
EOT character. Two EOT newline characters are sent
BREAK character (same as \K)
Collapse the octal digits (ddd) into a single character before sending.
The following example is shown below as two lines due to screen-width
limitations. As a typical example entry in Systems, it would
actually be one line:
host1 Any ACU 1200 ch6412 ""
login:--login: uucp word: sysuucp
In this example, host1 can be called at any time (Any)
using a phone connection (ACU) at 1200 baud. The phone
number is ch (which is defined in the Dialcodes file)
followed by 6412. Initially, the local system
expects nothing (indicated by "") and sends a
sequence of four carriage returns with
two-second delays separating them (\r\d\r\d\r\d\r).
This is typical
for a remote system that must read characters before presenting a login
prompt. Finally, the login is executed, using login ID uucp
and password sysuucp.
Contains information about available devices
Contains dial-code abbreviations
Contains information about modems used for uucp
Commands: ct(1), cu(1), uutry(1), uucp(1),
- Fields in the Systems File
- RELATED INFORMATION
This document was created by
using the manual pages.
Time: 02:40:08 GMT, October 02, 2010