The Systems File

Now that the device has been defined in Devices, and the connection to the device, either modem, or remote system has been verified using the cu command, the Systems file can be set up to allow calls to be made by uucico and cu.

The Systems file defines the names of the UUCP systems that your system can connect to. In other words, you don’t have to make an entry for every machine that might call you (you can use anonymous UUCP), but only for those machines that you want to call your machine. Each entry is in the format:

System_Name Schedule Type Speed Phone_Number Login_script

For example, consider this entry in unilabs’ system file:

gateway Any INTACU 1200 9999999 ““ \d\r\d\r ogin: nuucp22 word: testing

The System_Name (gateway) is the name of the remote machine you are trying to contact. Many UUCP implementations truncate the system name to seven characters. For this reason, this name should be unique to seven characters. More modern systems, however, allow the use of longer names.

Time_to_Call is the calling schedule for this machine. That is, you can restrict when this machine can be called. This can be handy if the link between the machines is expensive. This field can contain a number of different values and components, including the day of the week, and the start and end hour. The time or schedule field uses the following values to indicate the day of the week:

The time specification for the start and end time is given using the 24-hour clock to distinguish between 5:00 a.m. and 5:00 p.m. The specification can span midnight, as in 2310–0700, allowing calls from 11:10 p.m. to 7:00 a.m. You should, however, consider how you select times with uucico. uucico itself interprets the times on a same day basis. In the previous example, uucico interprets the times to allow calls from 0000–0700, and 2310–2359 on the same day. This is really only a problem if you combine the time with a specification such as Wk, or specific days. For example, Wk2310–0700 works for Mon–Fri, but does not allow calls after 2359 Friday night, until 0000 Monday morning. Consequently, careful thought must be given to the call specification.

The schedule fields can have only a day specification, with no time value, which means that the system can call any time of the day. The time subfields, however, must have a day specification. If you want to allow calls between 2310–0700 every day of the week, for example, you would use the specification Any2310–0700 in the schedule field.

It also is possible to have multiple calling periods for a single system by separating each of the periods with a comma. Suppose, for example, that you want to allow calling only between 2300–0700 weekdays, and any time on the weekends. This would be written as Wk2300-0700,SaSu. This multiple time specification is not supported in all implementations. Consequently, some experimentation may be required.

The schedule field also may specify an optional retry number, which is used to change the default number of minutes before another attempt will be made to call this system. BNU systems default to a ten-minute delay (600 seconds), which increases with each unsuccessful connection. To specify this retry, follow the schedule with a semicolon, and the retry period in minutes, as in Any;2—a retry period of 2 minutes. This doesn’t invoke uucico any quicker, but instructs uucico the next time it is invoked to wait for this period of time to elapse before attempting to connect again.

The Type field specifies the name of the device that will be used; this device must also appear in the Devices file. Any name defined in the Devices file is valid here. To use a TCP connection, the device named here is TCP, and includes the protocol to be used. After the device is named, an optional field enables you to specify the protocol for the call. The default is to use protocol “g,” which is not terribly efficient when using a high-speed reliable transport such as TCP/IP. For this purpose, the “e” protocol was created. Available protocols are discussed in the final part of this chapter. In addition, the TLI and TLIS transports can also be used with correct configuration.

The Speed field is used to define the speed of the connection to this system. This is defined in baud for the connection. No keywords are permitted.

Phone is the actual number to dial and is used with modems. Direct connections mark this field with a hyphen (-). The phone number can include any number of things, including dialcodes and support for calling card numbers. If, for example, you must dial 9 to get an outside line, you need to pause the dialer to wait for the secondary dial tone. The equal sign (=) is placed in the number to provide a delay. To access an outside line, 9= can be placed in the phone number. In some implementations of modem software, the comma generates a pause. It might be necessary to review your modem’s documentation to determine the character for a delay.