Introduction to Taylor UUCP
***************************

   General introductions to UUCP are available, and perhaps one day I
will write one.  In the meantime, here is a very brief one that
concentrates on the programs provided by Taylor UUCP.

   Taylor UUCP is a complete UUCP package.  It is covered by the GNU
Public License, which means that the source code is always available.
It is composed of several programs; most of the names of these programs
are based on earlier UUCP packages.

`uucp'
     The `uucp' program is used to copy file between systems.  It is
     similar to the standard Unix `cp' program, except that you can
     refer to a file on a remote system by using `system!' before the
     file name.  For example, to copy the file `notes.txt' to the system
     `airs', you would say `uucp notes.txt airs!~/notes.txt'.  In this
     example `~' is used to name the UUCP public directory on `airs'.
     For more details, see See uucp: Invoking uucp.

`uux'
     The `uux' program is used to request the execution of a program on
     a remote system.  This is how mail and news are transferred over
     UUCP.  As with `uucp', programs and files on remote systems may be
     named by using `system!'.  For example, to run the `rnews' program
     on `airs', passing it standard input, you would say `uux -
     airs!rnews'.  The `-' means to read standard input and set things
     up such that when `rnews' runs on `airs' it will receive the same
     standard input.  For more details, see See uux: Invoking uux.

   Neither `uucp' nor `uux' actually do any work immediately.  Instead,
they queue up requests for later processing.  They then start a daemon
process which processes the requests and calls up the appropriate
systems.  Normally the system will also start the daemon periodically to
check if there is any work to be done.  The advantage of this approach
is that it all happens automatically.  You don't have to sit around
waiting for the files to be transferred.  The disadvantage is that if
anything goes wrong it might be a while before anybody notices.

`uustat'
     The `uustat' program does many things.  By default it will simply
     list all the jobs you have queued with `uucp' or `uux' that have
     not yet been processed.  You can use `uustat' to remove any of
     your jobs from the queue.  You can also it use it to show the
     status of the UUCP system in various ways, such as showing the
     connection status of all the remote systems your system knows
     about.  The system administrator can use `uustat' to automatically
     discard old jobs while sending mail to the user who requested
     them.  For more details, see See uustat: Invoking uustat.

`uuname'
     The `uuname' program by default lists all the remote systems your
     system knows about.  You can also use it to get the name of your
     local system.  It is mostly useful for shell scripts.  For more
     details, see See uuname: Invoking uuname.

`uulog'
     The `uulog' program can be used to display entries in the UUCP log
     file.  It can select the entries for a particular system or a
     particular user.  You can use it to see what has happened to your
     queued jobs in the past.  For more details, see See uulog: Invoking uulog.

`uuto'
`uupick'
     `uuto' is a simple shell script interface to `uucp'.  It will
     transfer a file, or the contents of a directory, to a remote
     system, and notify a particular user on the remote system when it
     arrives.  The remote user can then retrieve the file(s) with
     `uupick'.  For more details, see See uuto: Invoking uuto, and
     see See uupick: Invoking uupick.

`cu'
     The `cu' program can be used to call up another system and
     communicate with it as though you were directly connected.  It can
     also do simple file transfers, though it does not provide any
     error checking.  For more details, See cu: Invoking cu.

   These eight programs just described, `uucp', `uux', `uuto',
`uupick', `uustat', `uuname', `uulog', and `cu' are the user programs
provided by Taylor UUCP.  `uucp', `uux', and `uuto' add requests to the
work queue, `uupick' extracts files from the UUCP public directory,
`uustat' examines the work queue, `uuname' examines the configuration
files, `uulog' examines the log files, and `cu' just uses the UUCP
configuration files.

   The real work is actually done by two daemon processes, which are
normally run automatically rather than by a user.

`uucico'
     The `uucico' daemon is the program which actually calls the remote
     system and transfers files and requests.  `uucico' is normally
     started automatically by `uucp' and `uux'.  Most systems will also
     start it periodically to make sure that all work requests are
     handled.  `uucico' checks the queue to see what work needs to be
     done, and then calls the appropriate systems.  If the call fails,
     perhaps because the phone line is busy, `uucico' leaves the
     requests in the queue and goes on to the next system to call.  It
     is also possible to force `uucico' to call a remote system even if
     there is no work to be done for it, so that it can pick up any
     work that may be queued up remotely.  For more details, see 
See uucico: Invoking uucico.

`uuxqt'
     The `uuxqt' daemon processes execution requests made by the `uux'
     program on remote systems.  It also processes requests made on the
     local system which require files from a remote system.  It is
     normally started by `uucico'.  For more details, see See uuxqt: Invoking uuxqt.

   Suppose you, on the system `bantam', want to copy a file to the
system `airs'.  You would run the `uucp' command locally, with a
command like `uucp notes.txt airs!~/notes.txt'.  This would queue up a
request on `bantam' for `airs', and would then start the `uucico'
daemon.  `uucico' would see that there was a request for `airs' and
attempt to call it.  When the call succeeded, another copy of `uucico'
would be started on `airs'.  The two copies of `uucico' would tell each
other what they had to do and transfer the file from `bantam' to
`airs'.  When the file transfer was complete the `uucico' on `airs'
would move it into the UUCP public directory.

   UUCP is often used to transfer mail.  This is normally done
automatically by mailer programs.  When `bantam' has a mail message to
send to `ian' at `airs', it executes `uux - airs!rmail ian' and writes
the mail message to the `uux' process as standard input.  The `uux'
program, running on `bantam', will read the standard input and store
it, as well as the `rmail' request itself, on the work queue for
`airs'.  `uux' will then start the `uucico' daemon.  The `uucico'
daemon will call up `airs', just as in the `uucp' example, and transfer
the work request and the mail message.  The `uucico' daemon on `airs'
will put the files on a local work queue.  When the communication
session is over, the `uucico' daemon on `airs' will start the `uuxqt'
daemon.  `uuxqt' will see the request on the work queue, and will run
`rmail ian' with the mail message as standard input.  The `rmail'
program, which is not part of the UUCP package, is then responsible for
either putting the message in the right mailbox on `airs' or forwarding
the message on to another system.

   Taylor UUCP comes with a few other programs that are useful when
installing and configuring UUCP.

`uuchk'
     The `uuchk' program reads the UUCP configuration files and displays
     a rather lengthy description of what it finds.  This is useful when
     configuring UUCP to make certain that the UUCP package will do
     what you expect it to do.  For more details, see See uuchk: Invoking uuchk.

`uuconv'
     The `uuconv' program can be used to convert UUCP configuration
     files from one format to another.  This can be useful for
     administrators converting from an older UUCP package.  Taylor UUCP
     is able to read and use old configuration file formats, but some
     new features can not be selected using the old formats.  For more
     details, see See uuconv: Invoking uuconv.

`uusched'
     The `uusched' script is provided for compatibility with older UUCP
     releases.  It starts `uucico' to call, one at a time, all the
     systems for which work has been queued.  For more details, see
     See uusched: Invoking uusched.

`tstuu'
     The `tstuu' program is a test harness for the UUCP package; it can
     help check that the package has been configured and compiled
     correctly.  However, it uses pseudo-terminals, which means that it
     is less portable than the rest of the package.  If it works, it
     can be useful when initially installing Taylor UUCP.  For more
     details, see See tstuu: Testing the Compilation.