Content-type: text/html Man page of Systems


Section: Devices and Network Interfaces (4)
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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 example TCP,f.
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: Null character Backspace 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 Newline Carriage return Space character Tab backslash 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 communications links  


Daemons: uucico(8) Commands: ct(1), cu(1), uutry(1), uucp(1), uucpsetup(8) delim off



Fields in the Systems File

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Time: 02:40:08 GMT, October 02, 2010