The Systems File

The Systems File

The Systems file (/etc/uucp/Systems) contains the information needed by the uucico daemon to establish a communications link to a remote computer. Each entry in the file represents a computer that can call or be called by your computer. In addition, UUCP software by default is configured to prevent any computer that does not appear in this file from logging in to your computer. (Refer to "Other UUCP Files" for a description of the remote.unknown file.) More than one entry may be present for a particular computer. The additional entries represent alternative communications paths that are tried in sequential order.

Using the Sysfiles file, you can define several files to be used as Systems files. See "The Sysfiles File" for details.

Each entry in the Systems file has the following format:

System-name Time Type Class Phone Login

These fields are defined in the following sections.

The System-name Field

This field contains the node name of the remote computer.

The Time Field

This field is a string that indicates the day-of-week and time-of-day when the remote computer can be called. The format of the Time field is

day[time][;retry]

The day portion is a list of one or more day specifiers. These specifiers are listed below.

Su, Mo, Tu, We, Th, Fr, Sa: These abreviations stand for individual days of the week: Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday.
Wk: Specifies any weekday, Monday through Friday.
Any: Specifies any day.
Never: Specifies that this station never initiates calls to the remote computer.If the Time field is Never, your computer will never initiate a call to the remote computer. The call must be initiated by the remote computer. In other words, your computer is in a passive mode with respect to the remote computer. (For more information on permissions, see "The Permissions File".)

Here is an example of a Time field:

Wk1700-0800,Sa,Su

This example allows calls from 5:00 p.m. to 8:00 a.m., Monday through Friday, and any time Saturday and Sunday. The example would be an effective way to call only when phone rates are low, if immediate transfer is not critical.

The time portion should be a range of times such as 0800-1230. If no time portion is specified, any time of day is assumed to be allowed for the call. A time range that spans 0000 is permitted. For example, 0800-0600 means all times are allowed other than at times between 6 a.m. and 8 a.m.

An optional subfield, retry, is available to specify the minimum time (in minutes) before a retry, following a failed attempt. The default wait is 5 minutes after the first failure, 10 after the second, and so on until a delay of about 24 hours. If the retry subfield is present, that wait is used after every failure. The subfield separator is a semicolon (;). For example, "Any;9" is interpreted as "call any time, but wait at least 9 minutes before retrying after a failure occurs."

The Type Field

This field contains the device type that should be used to establish the communications link to the remote computer. The keyword used in this field is matched against the first field of Devices file entries:

Systems: eagle Any ACU,g D1200 3251 login:nuucp password: Oakgrass

Devices: ACU ttym2 - D1200 penril

You can define the protocol used to contact the station by adding it on to the Type field. The example just given shows how to attach the protocol g to the device type ACU. For direct connects, use the name of the station to which you are connecting. See "Device Protocols".

The Class Field

This field is used to indicate the transfer speed of the device used to establish the communications link. It may contain a letter and speed (for example, C1200, D1200) to differentiate between classes of dialers. (See the discussion of the Class field in "The Devices File".) Some devices can be used at any speed, so the keyword Any may be used. This field must match the Class field in the associated Devices file entry as shown here:

Systems: eagle Any ACU D1200 NY3251 login:nuucp password:Oakgrass

Devices: ACU ttym2 - D1200 penril

If information is not required for this field, use a hyphen as a place holder for the field.

The Phone Field

This field is used to provide the phone number (token) of the remote computer for automatic dialers. The phone number is made up of an optional alphabetic abbreviation and a numeric part. If an abbreviation is used, it must be one that is listed in the Dialcodes file. For example:

Systems: eagle Any ACU D1200 NY3251 login:nuucp password: Oakgrass

Dialcodes: NY 9=1212555

In this string, an equal sign (=) tells the ACU to wait for a secondary dial tone before dialing the remaining digits. A hyphen (-) in the string instructs the ACU to pause four seconds before dialing the next digit.

If your computer is connected to a modem switch, you may access other computers that are connected to that switch. The Systems file entries for these computers does not have a phone number in the Phone field. Instead, this field contains the token that must be passed on to the switch so it will know which computer your computer wishes to communicate with. This token is usually just the station name. The associated Devices file entry should have a \D at the end of the entry to ensure that this field is not translated by means of the Dialcodes file.

The Login Field

This field contains login information given as a series of fields and subfields of the format:

expect send

The send string is sent when the expect string is received. The expect field may be made up of subfields of the form:

expect[-send-expect]...

The send field is sent if the prior expect is not successfully read and the expect following the send is the next expected string. For example, with "login--login," UUCP expects the string "login." If UUCP receives that string, it goes on to the next field. If it does not receive the string, it sends nothing, followed by a new line, then looks for "login" again. If no characters are initially expected from the remote computer, the characters " " (null string) should be used in the first expect field. Note that all send fields are sent followed by a newline unless the send string is terminated with a \c.

Here is an example of a Systems file entry that uses an expect-send string:

owl Any ACU 1200 NY6013 "" \r login:-BREAK-login: uucpx word: xyzzy

This example means causes UUCP to send a carriage return and wait for the string "login:" If it doesn't receive the string, it sends a break character and waits for "login:" again. When it does receive the string "login," it sends the login name uucpx; waits to receive the string "word:" (the last part of "Password:"); and sends the password xyzzy.

Several escape sequences cause specific actions when they are a part of a string sent during the login sequence. These are the same escape sequences used in the Dialers file, listed in Table 7-2.