L.SYS(5)

NAME
L.sys - UUCP remote host description file

DESCRIPTION
The L.sys file is consulted by the UUCP daemon uucico(8) for information on remote systems. L.sys includes the system name, appropriate times to call, phone numbers, and a login and password for the remote system. L.sys is thus a privileged file, owned by the UUCP Administrator; it is accessible only to the Administrator and to the superuser.

Each line in L.sys describes one connection to one remote host, and has the form:

System  Times  Caller  Class  Device/Phone_Number  [Expect  Send]....

Fields can be separated by any number of blanks or tabs. Lines beginning with a `#' character are comments; long lines can be continued by appending a `\' character to the end of the line.

The first five fields (System through Device/Phone_Number) specify the hardware mechanism that is necessary to make a connection to a remote host, such as a modem or network. Uucico searches from the top down through L.sys to find the desired System; it then opens the L-devices(5) file and searches for the first available device with the same Caller, Class, and (possibly) Device. (``Available'' means that the device is ready and not being used for something else.) Uucico attempts a connection using that device; if the connection cannot be made (for example, a dialer gets a busy signal), uucico tries the next available device. If this also fails, it returns to L.sys to look for another line for the same System. If none is found, uucico gives up.

System is the hostname of the remote system. Every machine with which this system communicates via UUCP should be listed, regardless of who calls whom. Systems not listed in L.sys will not be permitted a connection. The local hostname should not appear here for security reasons.

Times is a comma-separated list of the times of the day and week that calls are permitted to this System. Times is most commonly used to restrict long distance telephone calls to those times when rates are lower. List items are constructed as:

	keywordhhmm-hhmm/grade;retry_time

Keyword is required, and must be one of:

Any Any time, any day of the week.

Wk  Any weekday. In addition, Mo, Tu, We, Th, Fr, Sa, and Su can be used for Monday through Sunday, respectively.

Evening
    When evening telephone rates are in effect, from 1700 to 0800 Monday through Friday, and all day Saturday and Sunday. Evening is the same as Wk1700-0800,Sa,Su.

Night
    When nighttime telephone rates are in effect, from 2300 to 0800 Monday through Friday, all day Saturday, and from 2300 to 1700 Sunday. Night is the same as Any2300-0800,Sa,Su0800-1700.

NonPeak
    This is a slight modification of Evening. It matches when the USA X.25 carriers have their lower rate period. This is 1800 to 0700 Monday through Friday, and all day Saturday and Sunday. NonPeak is the same as Any1800-0700,Sa,Su.

Never
    Never call; calling into this System is forbidden or impossible. This is intended for polled connections, where the remote system calls into the local machine periodically. This is necessary when one of the machines is lacking either dial-in or dial-out modems.

The optional hhmm-hhmm subfield provides a time range that modifies the keyword. hhmm refers to hours and minutes in 24-hour time (from 0000 to 2359). The time range is permitted to "wrap" around midnight, and will behave in the obvious way. It is invalid to follow the Evening, NonPeak, and Night keywords with a time range.

The grade subfield is optional; if present, it is composed of a `/' (slash) and single character denoting the grade of the connection, from 0 to 9, A to Z, or a to z. This specifies that only requests of grade grade or better will be transferred during this time. (The grade of a request or job is specified when it is queued by uucp or uux.) By convention, mail is sent at grade C, news is sent at grade d, and uucp copies are sent at grade n. Unfortunately, some sites do not follow these conventions, so it is not 100% reliable.

The retry_time subfield is optional; it must be preceded by a `;' (semicolon) and specifies the time, in minutes, before a failed connection may be tried again. (This restriction is in addition to any constraints imposed by the rest of the Time field.) By default, the retry time starts at 10 minutes and gradually increases at each failure, until after 26 tries uucico gives up completely (MAX RETRIES). If the retry time is too small, uucico may run into MAX RETRIES too soon.

Caller is the type of device used:

ACU Automatic call unit or auto-dialing modem such as the Hayes Smartmodem 1200 or Novation ``Smart Cat''. See L-devices for a list of supported modems.

DIR Direct connect; hardwired line (usually RS-232) to a remote system.

MICOM
    Micom Terminal Switch.

PAD X.25 PAD connection.

PCP GTE Telenet PC Pursuit. See L-devices for configuration details.

SYTEK
    Sytek high-speed dedicated modem port connection.

TCP Berkeley TCP/IP or 3Com UNET connection. These are mutually exclusive. TCP ports do not need entries in L-devices since all the necessary information is contained in L.sys. If several alternate ports or network connections should be tried, use multiple L.sys entries.

Class is usually the speed (baud) of the device, typically 300, 1200, or 2400 for ACU devices and 9600 for direct lines. Valid values are device dependent, and are specified in the L-devices file.

On some devices, the baud may be preceded by a non-numeric prefix. This is used in L-devices to distinguish among devices that have identical Caller and baud, but yet are distinctly different. For example, 1200 could refer to all Bell 212-compatible modems, V1200 to Racal-Vadic modems, and C1200 to CCITT modems, all at 1200 baud.

On TCP connections, Class is the port number (an integer number) or a port name from /etc/services that is used to make the connection. For standard Berkeley TCP/IP, UUCP normally uses port number 540.

Device/Phone_Number varies based on the Caller field. For ACU devices, this is the phone number to dial. The number may include: digits 0 through 9; # and * for dialing those symbols on tone telephone lines; - (hyphen) to pause for a moment, typically two to four seconds; = (equal sign) to wait for a second dial tone (implemented as a pause on many modems). Other characters are modem dependent; generally standard telephone punctuation characters (such as the slash and parentheses) are ignored, although uucico does not guarantee this.

The phone number can be preceded by an alphabetic string; the string is indexed and converted through the L-dialcodes(5) file.

For DIR devices, the Device/Phone_Number field contains the name of the device in /dev that is used to make the connection. There must be a corresponding line in L-devices with identical Caller, Class, and Device fields.

For TCP and other network devices, Device/Phone_Number holds the true network name of the remote system, which may be different from its UUCP name (although one would hope not).

Expect and Send refer to an arbitrarily long set of strings that alternately specify what to expect and what to send to login to the remote system once a physical connection has been established. A complete set of expect/send strings is referred to as an expect/send script. The same syntax is used in the L-devices file to interact with the dialer prior to making a connection; there it is referred to as a chat script. The complete format for one expect/send pair is:

	expect-timeout-send-expect-timeout   send

Expect and Send are character strings. Expect is compared against incoming text from the remote host; send is sent back when expect is matched. By default, the send is followed by a `\r' (carriage return). If the expect string is not matched within timeout seconds (default 45), then it is assumed that the match failed. The `expect-send-expect' notation provides a limited loop mechanism; if the first expect string fails to match, then the send string between the hyphens is transmitted, and uucico waits for the second expect string. This can be repeated indefinitely. When the last expect string fails, uucico hangs up and logs that the connection failed.

The timeout can (optionally) be specified by appending the parameter `~nn' to the expect string, when nn is the timeout time in seconds.

Backslash escapes that may be imbedded in the expect or send strings include:

	\b	Generate a 3/10 second BREAK.
	\bn	Where n is a single-digit number;
		generate an n/10 second BREAK.
	\c	Suppress the \r at the end of a send string.
	\d	Delay; pause for 1 second. (Send only.)
	\r	Carriage Return.
	\s	Space.
	\n	Newline.
	\xxx	Where xxx is an octal constant;
		denotes the corresponding ASCII character.

As a special case, an empty pair of double-quotes "" in the expect string is interpreted as ``expect nothing''; that is, transmit the send string regardless of what is received. Empty double-quotes in the send string cause a lone `\r' (carriage return) to be sent.

One of the following keywords may be substituted for the send string:

	BREAK	Generate a 3/10 second BREAK
	BREAKn	Generate an n/10 second BREAK
	CR	Send a Carriage Return (same as "").
	EOT	Send an End-Of-Transmission character, ASCII \004.
		Note that this will cause most hosts to hang up.
	NL	Send a Newline.
	PAUSE	Pause for 3 seconds.
	PAUSEn	Pause for n seconds.
	P_ODD	Use odd parity on future send strings.
	P_ONE	Use parity one on future send strings.
	P_EVEN	Use even parity on future send strings. (Default)
	P_ZERO	Use parity zero on future send strings.

Finally, if the expect string consists of the keyword ABORT, then the string following is used to arm an abort trap. If that string is subsequently received any time prior to the completion of the entire expect/send script, then uucico will abort, just as if the script had timed out. This is useful for trapping error messages from port selectors or front-end processors such as ``Host Unavailable'' or ``System is Down.''

For example:

	""  ""  ogin:--ogin:  nuucp  ssword:  ufeedme

This is executed as, ``When the remote system answers, expect nothing. Send a carriage return. Expect the remote to transmit the string `ogin:'. If it doesn't within 45 seconds, send another carriage return. When it finally does, send it the string `nuucp'. Then expect the string `ssword:'; when that is received, send `ufeedme'.''

FILES
/etc/uucp/L.sys
/etc/uucp/UUAIDS/L.sys    L.sys example

SEE ALSO
uucp(1), uux(1), L-devices(5), services(5), uucico(8)

BUGS
``ABORT'' in the send/expect script is expressed ``backwards,'' that is, it should be written `` expect ABORT'' but instead it is `` ABORT expect''.

Several of the backslash escapes in the send/expect strings are confusing and/or different from those used by AT&T and Honey-Danber UUCP. For example, `\b' requests a BREAK, while practically everywhere else `\b' means backspace. `\t' for tab and `\f' for formfeed are not implemented. `\s' is a kludge; it would be more sensible to be able to delimit strings with quotation marks.