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README
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README
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** lftp-4.5.x
This package `lftp' contains the following components:
lftp
sophisticated command line file transfer program (ftp/http client,
also supports several other protocols).
lftpget
shell script for downloading by URL, it calls `lftp -c'.
lftp is written in C++ and uses a cooperative-threaded model.
lftp
~~~~
lftp is sophisticated file transfer program with command line interface. It
supports FTP, HTTP, FISH, SFTP and FILE (local FS) protocols. GNU Readline
library is used for input. BitTorrent protocol is supported as built-in
`torrent' command.
Low level stuff supported: ftp proxy, http proxy, ftp over http, opie/skey,
fxp transfers, automatic retrying on non-fatal errors and timeouts, ipv6,
socks, http/1.1, sftp v3-v6. See FEATURES for more detailed list of
features.
Every operation in lftp is reliable, that is any non-fatal error is ignored
and the operation is retried. 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.
lftp has shell-like command syntax allowing you to launch several commands
in parallel in background (&). It is also 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
(c-z) and back with command `wait' (or `fg' which is alias to `wait'). To
list running jobs, use command `jobs'. Some commands allow redirecting
their output (cat, ls, ...) to file or via pipe to external command.
Commands can be executed conditionally based on termination status of
previous command (&&, ||).
If you exit lftp when some jobs are not finished yet, lftp will move itself
to nohup mode in background. The same happens when you have a real modem
hangup or when you close an xterm. It is possible to attach to backgrounded
lftp instance using `attach' command in lftp, e.g. `lftp -c attach'.
lftp has builtin mirror which can download or update a whole directory
tree. There is also reverse mirror (mirror -R) which uploads or updates a
directory tree on server. It is also possible to synchronize two servers,
FXP is used automatically if possible.
There is command `at' to launch a job at specified time in current context,
command `queue' to queue commands for sequential execution for current
server, and much more.
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 3' to see
only greeting messages and error messages. if ~/.lftp directory does not
exist, XDG directories are used instead: ~/.config/lftp, ~/.local/share/lftp
and ~/.cache/lftp.
lftp has a number of settable variables. You can use `set -a' to see all
variables and their values or `set -d' to see list of defaults. Variable
names can be abbreviated and prefix can be omitted unless the rest becomes
ambiguous.
Use command `help' or read documentation (man lftp) to learn more.
If lftp was compiled with ssl support, then it includes software developed
by the OpenSSL Project for use in the OpenSSL Toolkit.
(http://www.openssl.org/)
Where to get
~~~~~~~~~~~~
By FTP:
ftp://ftp.yar.ru/pub/source/lftp/
By HTTP:
http://lftp.yar.ru/ftp/
By GIT (development):
https://github.com/lavv17/lftp
See also the home page `http://lftp.yar.ru/'.
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.
There are also some useful classes: Timer, TimeDate, *Buffer, xstring,
xarray, xlist, xmap, xheap, Ref etc. Timers are ordered using a heap data
structure. Primitive classes were implemented with performance and low
memory consumption in mind. Standard C++ library is not used, since lftp
development started when it was not so standard yet (and boost did not even
exist).
Access to remote files is performed via FileAccess class, which is base
class for all protocols. NetAccess is for network file access. There is
also LocalAccess for local files access. SSH_Access is for SSH based
protocols: FISH and SFTP.
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.
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 Solaris(gcc), Linux, FreeBSD, NetBSD,
SCO v5.0(gcc), IRIX(gcc), Tru64(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 mailman; to subscribe, send mail to lftp-subscribe@uniyar.ac.ru;
to send letters to the list, send them to lftp@uniyar.ac.ru; to
unsubscribe, send mail to lftp-unsubscribe@uniyar.ac.ru. This is a low
volume list. See also http://univ.uniyar.ac.ru/mailman/listinfo/lftp.
There is also list lftp-devel@uniyar.ac.ru for snapshot announcements and
other development.
These lists are archived at
http://www.mail-archive.com/lftp%40uniyar.ac.ru/
http://www.mail-archive.com/lftp-devel%40uniyar.ac.ru/
You can also submit pull requests or issues to GitHub:
https://github.com/lavv17/lftp
Author
~~~~~~
Author: Alexander V. Lukyanov <lav@yars.free.net>
My home page: http://lav.yar.ru/
My other E-Mails: lav@yar.ru, lav@netis.ru, lavv17f@gmail.com
Other people have contributed to lftp development, see the THANKS file.
Comments and bug reports are welcome. Please send them to the list:
<lftp@uniyar.ac.ru>. Subscribe if you want your messages to be sent to the
list quickly.
License
~~~~~~~
Copyright (c) 1996-2014 by Alexander V. Lukyanov (lav@yars.free.net)
LFTP is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with LFTP. If not, see <http://www.gnu.org/licenses/>.