README

** lftp-2.1

This package `lftp' contains the following components:

   lftp
      cool command line ftp client.
      
   lftpget
      shell script for downloading by URL, calls `lftp -c'.

   ftpget
      a simple non-interactive tool for downloading files (deprecated)

These programs are written in C++, in a cooperative-threaded model.


lftp
~~~~
lftp is quite a powerful ftp client. It uses GNU readline to read
commands. It uses shell-like command syntax allowing you to launch
several commands in parallel in background (&).

Some commands allow redirecting its output (cat, ls) to file or via
pipe to external command. Commands can be started conditionally based
on termination status of previous command (&&, ||). Also, it is
possible to group commands within () and execute them in background.
All background jobs are executed in the same single process. You can
bring a foreground job to background with ^Z and back with command
`wait' (or `fg' which is alias to `wait').

When you think you are done but some jobs are not yet finished, you
can just exit and lftp will move itself to nohup mode in background.
The same happens when you have a real hangup.

lftp has reliable put, reput, mirror, and many other commands. Use
command `help' or read documentation to learn more.

Every operation in lftp is reliable, that is any not fatal error is
ignored and the operation is repeated. So if downloading breaks, it
will be restarted from the point automatically. Even if ftp server
does not support REST command, lftp will try to retrieve the file from
the very beginning until the file is transferred completely.


On startup, lftp executes /etc/lftp.conf and then ~/.lftprc and
~/.lftp/rc. You can place aliases and `set' commands there. Some
people prefer to see full protocol debug, use `debug' to turn the
debug on. Use `debug 0' to see only greeting messages and error
messages.

lftp has a number of settable variables (you can use `set -a' to
see all variables and their values), here are some:
 * cmd:csh-history - (bool) enables csh-like history expansion
 * cmd:long-running - (seconds) time of command execution, which is
considered as `long' and a beep is done before next prompt. 0 means
off.
 * cmd:ls-default - (string) default ls argument
 * cmd:prompt - (string) prompt. lftp recognizes some bash escapes,
such as \u, \h, \w.
 * cmd:remote-completion - (bool) whether to use remote completion.
 * net:idle - (seconds) close idle connections locally after this time
 * net:max-retries - (num) limit maximum number of operation retries
(default 0=unlimited)
 * ftp:passive-mode - (bool) passive mode ftp
 * ftp:proxy - (string) ftp proxy
 * net:reconnect-interval - (seconds) minimal time between reconnects.
 * net:relookup-always - (bool) relookup host address each time before
connecting
 * ftp:sync-mode - (bool) send one command at a time and wait for
response. Might be necessary to set it to `on' if buggy ftp server or
router is used. Setting it to `off' speeds up command/response
exchange with server, especially if ping time is significant.
 * net:timeout - (seconds) network protocol timeout

Variable names can be abbreviated and prefix can be omitted unless the
rest becomes ambiguous.

See man page for other variables. You can also use `set -a' to see all
current valiables and their values, and `set -d' to see default values
of all variables.

Where to get
~~~~~~~~~~~~
By FTP:
	ftp://ftp.yars.free.net/pub/software/unix/net/ftp/client/lftp/
	ftp://metalab.unc.edu/pub/Linux/system/network/file-transfer/
By HTTP:
	http://ftp.yars.free.net/pub/software/unix/net/ftp/client/lftp/
	http://metalab.unc.edu/pub/Linux/system/network/file-transfer/
By CVS:
	CVSROOT=:pserver:anonymous@swing.yars.free.net:/home/lav/cvsroot
	export CVSROOT
	cvs login (empty password, just hit enter)
	cvs -z9 co -r lftp-2-0-3 lftp (if you omit -r option, you'll get
		latest development sources)
		
See also home page `http://ftp.yars.free.net/projects/lftp/'.

Internals
~~~~~~~~~
All this is based on SMTask class which implements non-preemptive
multitasking via Do method. The method Do does a little bit of work,
sets wake up condition (block member) and returns.

The class Ftp allows reliable deliver of files via ftp protocol, it hides
all the details from application and allows asynchronous operation.
Reconnect and reget are done as necessary. It can also speed up ftp
operations by sending several commands at once and then checking all the
responses. It seems this sometimes does not work, so it is disabled by
default. To turn it on, use `set sync-mode n' in lftp or --async-mode for
ftpget.

Note that sending several commands is considered as violation or
protocol, but RFC959 says: ``The user-process sending another command
before the completion reply would be in violation of protocol; but
server-FTP processes should queue any commands that arrive while a
preceding command is in progress.''

It is known that some network software dealing with address
translation works incorrectly in case of several FTP commands in one
network packet.


Systems
~~~~~~~
The package is known to compile on Solaris2.5(gcc), Linux, FreeBSD,
SCO v5.0(gcc), IRIX(gcc) and other systems. If you can't compile it on
your system, let me know. It is possible that lftp version 2.0 can be
compiled with non-gcc compilers since it does not have gcc-isms, and
it was successfully compiled by Sun C++ v5.0 compiler using
CXXFLAGS="-compat=4 -features=bool".


Mailing list
~~~~~~~~~~~~
There is a mailing list for discussion of lftp and announcements. It
is managed by majordomo; to subscribe, send mail to
majordomo@uniyar.ac.ru with `subscribe lftp' in body of message; to
send letters to the list, send them to lftp@uniyar.ac.ru; to
unsubscribe, send mail to majordomo@uniyar.ac.ru with `unsubscribe
lftp' in body of message. This is low volume list.

There is also list lftp-devel@uniyar.ac.ru for snapshot announcements
and other development.


Author
~~~~~~
Author: Alexander V. Lukyanov <lav@yars.free.net>
Postal address: Aviatorov st. 80-45, Yaroslavl 150051, Russia

Comments and bug reports are welcome.