[school-discuss] rsync vs ftp (was: linuxconf)

[Michael Shigorin <mike@xxxxxxxxxxx>]

On Wed, Oct 17, 2007 at 04:26:38PM -0700, marilyn@ wrote:
> Thanks for your information too!  You see I never even knew
> that is was a screwy thing to reply and erase the subject - so
> cool - I will remember that.  :)

Welcome ;)

> If you guys who are system administrator folks saw me in
> action, I am sure you would be horrified.  I just sort of
> install a bunch of crap, see if it works, if not I reformat and
> install something different.

Well that's sort of what I've been playing to... okay yesterday:
couple recent desktop systems, and couple recent desktop linuxen,
SLED10 and ALT Desktop (4.0.1 beta).  Just erasing everything
a couple times and starting over under a different angle. :)

> You see, I do not even know what ?rsync-over-ssh as r/w
> transport? is . . . but since you say it is cool, I will read
> up on it.

Sorry.

"r/w" is "read/write"; that is, when someone can modify something.

"r/o" is "read only" -- when no-one can modify anything.

FTP is quite horrible a protocol, too complex but still lacking
many features which appear in RSYNC; and it's rather clear-text
(there is TLS-based authentication and SFTP -- that add
encryption to login/password stage or the whole session --
but these haven't really gained much traction).

rsync is very good at keeping directories in sync, and ssh is
de-facto standard for "generic" wire crypto; you can use them
both to sync local directory to say website root on a server:

rsync -Pav --delete-after --bwlimit=60 ~/website/ user@xxxxxxxxx:/www/web.si.te/html/

which would synchronize utilizing partial uploads when
neccessary, archival options (that is, file times and permissions
will be transferred and set too if possible), some nice verbosity
and using no more than 60 Kilobytes per second in bandwidth
(sparing the rest of DSL).  The files absent in original will
be removed in destination after content sync finishes.

In this form it will automatically use ssh (see also "-e"
option in man rsync) to login to my.server as "user".  Thus
the connection (both auth part and data itself) will be
encrypted; ssh is very aptly used with public keys (see 
man ssh-keygen) and ~/.ssh/config (man ssh_config).

There's grsync, a GUI frontend for rsync, but I guess students
might be interested in scripting around -- at least for tasks
like maintaining a website it's quite reasonable to do backups
at the same time.

There's also "unison" utility which implies that none of the
directories is _the_ original one -- but rather that both can
change in time but must be kept in sync when needed.

-- 
 ---- WBR, Michael Shigorin <mike@xxxxxxxxxxx>
  ------ Linux.Kiev http://www.linux.kiev.ua/
 ----       Oct 26--27, Kiev, Ukraine:
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