- always flush the IO write buffer when reading

[rsync/rsync.git] / rsync.yo

mailto(rsync-bugs@samba.anu.edu.au)
manpage(rsync)(1)(13 May 1998)()()
manpagename(rsync)(faster, flexible replacement for rcp)
manpagesynopsis()

rsync [options] [user@]host:path path

rsync [options] path [user@]host:path

rsync [options] path path

rsync [options] [user@]host::path path

rsync [options] path [user@]host::path

manpagedescription()

rsync is a program that behaves in much the same way that rcp does,
but has many more options and uses the rsync remote-update protocol to
greatly speedup file transfers when the destination file already
exists.

The rsync remote-update protocol allows rsync to transfer just the
differences between two sets of files across the network link, using
an efficient checksum-search algorithm described in the technical
report that accompanies this package.

Some of the additional features of rsync are:

itemize(
  it() support for copying links, devices, owners, groups and permissions
  it() exclude and exclude-from options similar to GNU tar
  it() a CVS exclude mode for ignoring the same files that CVS would ignore
  it() can use any transparent remote shell, including rsh or ssh
  it() does not require root privileges
  it() pipelining of file transfers to minimize latency costs
  it() support for anonymous or authenticated rsync servers (ideal for
       mirroring)
)

manpagesection(GENERAL)

There are five different ways of using rsync. They are:

itemize(
	it() for copying local files. This is invoked when neither
	     source nor destination path contains a : separator

	it() for copying from the local machine to a remote machine using
	a remote shell program as the transport (such as rsh or
	ssh). This is invoked when the destination path contains a
	single : separator.

	it() for copying from a remote machine to the local machine
	using a remote shell program. This is invoked when the local path
	contains a : separator.

	it() for copying from a remote rsync server to the local
	machine. This is invoked when the source path contains a ::
	separator. 

	it() for copying from the local machine to a remote rsync
	server. This is invoked when the destination path contains a ::
	separator. 
)

Note that in all cases at least one of the source and destination
paths must be local.

manpagesection(SETUP)

See the file README for installation instructions.

Once installed you can use rsync to any machine that you can use rsh
to.  rsync uses rsh for its communications, unless both the source and
destination are local.

You can also specify a alternative to rsh, by either using the -e
command line option, or by setting the RSYNC_RSH environment variable.

One common substitute is to use ssh, which offers a high degree of
security.

Note that rsync must be installed on both the source and destination
machines. 

manpagesection(USAGE)

You use rsync in the same way you use rcp. You must specify a source
and a destination, one of which may be remote.

Perhaps the best way to explain the syntax is some examples:

quote(rsync *.c foo:src/)

this would transfer all files matching the pattern *.c from the
current directory to the directory src on the machine foo. If any of
the files already exist on the remote system then the rsync
remote-update protocol is used to update the file by sending only the
differences. See the tech report for details.

quote(rsync -avz foo:src/bar /data/tmp)

recursively transfer all files from the directory src/bar on the
machine foo into the /data/tmp/bar directory on the local machine. The
files are transferred in "archive" mode, which ensures that symbolic
links, devices, attributes, permissions, ownerships etc are preserved
in the transfer.  Additionally compression will be used to reduce the
size of data portions of the transfer.

quote(rsync -avz foo:src/bar/ /data/tmp)

With a trailing slash on the source this behavior changes to transfer
all files from the directory src/bar on the machine foo into the
/data/tmp/.  With a trailing / on a source name it means "copy the
contents of this directory".  Without a trailing slash it means "copy
the directory". This difference becomes particularly important when
using the --delete option.

You can also use rsync in local-only mode, where both the source and
destination don't have a ':' in the name. In this case it behaves like
an improved copy command.


manpagesection(CONNECTING TO AN RSYNC SERVER)

It is also possible to use rsync without using rsh or ssh as the
transport. In this case you will connect to a remote rsync server
running on TCP port 873. 

Using rsync in this was is the same as using it with rsh or ssh except
that:

itemize(
	it() you use a double colon :: instead of a single colon to
	separate the hostname from the path. 

	it() the remote server may print a message of the day when you
	connect

	it() if you specify no path name on the remote server then the
	list of accessible paths on the server will be shown.
)

Some paths on the remote server may require authentication. If so then
you will receive a password prompt when you connect. You can avoid the
password prompt by setting the environment variable RSYNC_PASSWORD to
the password you want to use. This may be useful when scripting rsync.

manpagesection(RUNNING AN RSYNC SERVER)

An rsync server is configured using a config file which by default is
called /etc/rsyncd.conf. Please see the rsyncd.conf(5) man page for more
information. 

manpagesection(EXAMPLES)

Here are some examples of how I use rsync.

To backup my wife's home directory, which consists of large MS word
files and mail folders I use a cron job that runs

quote(rsync -Cavz . arvidsjaur:backup)

each night over a PPP link to a duplicate directory on my machine
"arvidsjaur".

To synchronize my samba source trees I use the following Makefile
targets:

quote(      get:nl()
       rsync -avuzb --exclude '*~' samba:samba/ .

      put:nl()
       rsync -Cavuzb . samba:samba/

      sync: get put)

this allows me to sync with a CVS directory at the other end of the
link. I then do cvs operations on the remote machine, which saves a
lot of time as the remote cvs protocol isn't very efficient.

I mirror a directory between my "old" and "new" ftp sites with the
command

quote(rsync -az -e ssh --delete ~ftp/pub/samba/ nimbus:"~ftp/pub/tridge/samba")

this is launched from cron every few hours.

manpageoptions()

rsync uses the GNU long options package. Many of the command line
options have two variants, one short and one long.  These are shown
below separated by commas. Some options only have a long variant.

startdit()
dit(bf(-h, --help)) Print a short help page describing the options
available in rsync

dit(bf(--version)) print the rsync version number and exit

dit(bf(-v, --verbose)) This option increases the amount of information you
are given during the transfer.  By default rsync works silently. A
single -v will give you information about what files are being
transferred and a brief summary at the end. Two -v flags will give you
information on what files are being skipped and slightly more
information at the end. More than two -v flags should only be used if
you are debugging rsync

dit(bf(-I, --ignore-times)) Normally rsync will skip any files that are
already the same length and have the same time-stamp. This option turns
off this behavior.

dit(bf(-c, --checksum)) This forces the sender to checksum all files using
a 128-bit MD4 checksum before transfer. The checksum is then
explicitly checked on the receiver and any files of the same name
which already exist and have the same checksum and size on the
receiver are skipped.  This option can be quite slow.

dit(bf(-a, --archive)) This is equivalent to -rlptDog. It is a quick way
of saying I want recursion and want to preserve everything.

dit(bf(-r, --recursive)) This tells rsync to copy directories recursively

dit(bf(-R, --relative)) Use relative paths. This means that the full path
names specified on the command line are sent to the server rather than
just the last parts of the filenames. This is particularly useful when
you want to sent several different directories at the same time. For
example if you used the command

verb(rsync foo/bar/foo.c remote:/tmp/)

then this would create a file called foo.c in /tmp/ on the remote
machine. If instead you used

verb(rsync -R foo/bar/foo.c remote:/tmp/)

then a file called /tmp/foo/bar/foo.c would be created on the remote
machine. The full path name is preserved.

dit(bf(-b, --backup)) With this option preexisting destination files are
renamed with a ~ extension as each file is transferred.  You can
control the backup suffix using the --suffix option.

dit(bf(-u, --update)) This forces rsync to skip any files for which the
destination file already exists and has a date later than the source
file.

dit(bf(-l, --links)) This tells rsync to recreate symbolic links on the
remote system  to  be the same as the local system. Without this
option all symbolic links are skipped.

dit(bf(-L, --copy-links)) This tells rsync to treat symbolic links just
like  ordinary files.

dit(bf(-H, --hard-links)) This tells rsync to recreate hard  links  on
the  remote system  to  be the same as the local system. Without this
option hard links are treated like regular files.

Note that rsync can only detect hard links if both parts of the link
are in the list of files being sent.

This option can be quite slow, so only use it if you need it.

dit(bf(-W, --whole-file)) With this option the incremental rsync algorithm
is  not used  and  the whole file is sent as-is instead. This may be
useful when using rsync with a local machine.

dit(bf(-p, --perms)) This option causes rsync to update the remote
permissions to be the same as the local permissions.

dit(bf(-o, --owner)) This option causes rsync to update the  remote  owner
of the  file to be the same as the local owner. This is only available
to the super-user.

dit(bf(-g, --group)) This option causes rsync to update the  remote  group
of the file to be the same as the local group.

dit(bf(-D, --devices)) This option causes rsync to transfer character and
block device information to the remote system to recreate these
devices. This option is only available to the super-user.

dit(bf(-t, --times)) This tells rsync to transfer modification times along
with the files and update them on the remote system

dit(bf(-n, --dry-run)) This tells rsync to not do any file transfers,
instead it will just report the actions it would have taken.

dit(bf(-S, --sparse)) Try to handle sparse files efficiently so they take
up less space on the destination.

dit(bf(-x, --one-file-system)) This tells rsync not to cross filesystem
boundaries  when recursing.  This  is useful for transferring the
contents of only one filesystem.

dit(bf(--delete)) This tells rsync to delete any files on the receiving
side that aren't on the sending side. This option can be dangerous if
used incorrectly!

It is a very good idea to run first using the dry run option (-n) to
see what files would be deleted to make sure important files aren't
listed.

rsync 1.6.4 changed the behavior of --delete to make it less
dangerous.  rsync now only scans directories on the receiving side
that are explicitly transferred from the sending side.  Only files in
these directories are deleted.

Still, it is probably easy to get burnt with this option.  The moral
of the story is to use the -n option until you get used to the
behavior of --delete.

NOTE: It also may delete files on the destination if the sending side
can't open them or stat them. This is a bug that hopefully will be
fixed in a future release.

dit(bf(--force)) This options tells rsync to delete directories even if
they are not empty.  This applies to both the --delete option and to
cases where rsync tries to copy a normal file but the destination
contains a directory of the same name. Normally rsync will refuse to
do a recursive directory deletion in such cases, by using --force
the recursive deletion will be done.

Use this option with caution!

dit(bf(-B , --block_size BLOCKSIZE)) This controls the block size used in
the rsync algorithm. See the technical report for details.

dit(bf(-e, --rsh COMMAND)) This option allows you to choose an alternative
remote shell program to use for communication between the local and
remote copies of rsync. By default rsync will use rsh, but you may
like to instead use ssh because of its high security.

You can also choose the remote shell program using the RSYNC_RSH
environment variable.

dit(bf(--rsync-path PATH)) Use this to specify the path to the copy of
rsync on the remote machine. Useful when its not in your path.

dit(bf(--exclude FILE)) This option allows you to selectively exclude
certain files from the list of files to be transferred. This is most
useful in combination with a recursive transfer.

The option FILE can either be a file name or a shell wildcard
expression. If it is a directory name then rsync will not recurse into
directories of that name.

You may use as many --exclude options on the command line as you like
to build up the list of files to exclude.

If the filename is a single ! then the exclude list is reset.

dit(bf(--exclude-from FILE)) This option is similar to the --exclude
option, but instead it adds all filenames listed in the file FILE to
the exclude list.

dit(bf(-C, --cvs-exclude)) This is a useful shorthand for excluding a
broad range of files that you often don't want to transfer between
systems. It uses the same algorithm that CVS uses to determine if
a file should be ignored.

The exclude list is initialized to:

quote(RCS SCCS CVS CVS.adm RCSLOG cvslog.* tags TAGS .make.state
.nse_depinfo *~ #* .#* ,* *.old *.bak *.BAK *.orig *.rej .del-*
*.a *.o *.obj *.so *.Z *.elc *.ln core)

then files listed in a $HOME/.cvsignore are added to the list and any
files listed in the CVSIGNORE environment variable (space delimited).

Finally in each directory any files listed in the .cvsignore file in
that directory are added to the list.

dit(bf(--suffix SUFFIX)) This option allows you to override the default
backup suffix used with the -b option. The default is a ~.

dit(bf(--csum-length LENGTH)) By default the primary checksum used in
rsync is a very strong 16 byte MD4 checksum. In most cases you will
find that a truncated version of this checksum is quite efficient, and
this will decrease the size of the checksum data sent over the link,
making things faster.

You can choose the number of bytes in the truncated checksum using the
--csum-length option. Any value less than or equal to 16 is valid.

Note that if you use this option then you run the risk of ending up
with an incorrect target file. The risk with a value of 16 is
microscopic and can be safely ignored (the universe will probably end
before it fails) but with smaller values the risk is higher.

dit(bf(-T, --temp-dir DIR)) This options instructs rsync to use DIR as a
scratch directory when creating a temporary copies of the files
transferred on the receiving side.  The default behavior is to create
the temporary files in the receiving directory.

dit(bf(-z, --compress)) With this option, rsync compresses any data from
the source file(s) which it sends to the destination machine.  This
option is useful on slow links.  The compression method used is the
same method that gzip uses.

Note this this option typically achieves better compression ratios
that can be achieved by using a compressing remote shell, or a
compressing transport, as it takes advantage of the implicit
information sent for matching data blocks.

dit(bf(--numeric-ids)) With this option rsync will transfer numeric group
and user ids rather than using user and group names and mapping them
at both ends.

By default rsync will use the user name and group name to determine
what ownership to give files. The special uid 0 and the special group
0 and never mapped via user/group names even if the --numeric-ids
option is not specified.

If a user or group name does not exist on the destination system then
the numeric id from the source system is used instead.

dit(bf(--timeout)) This option allows you to set a maximum IO timeout in
seconds. If no data is transferred for the specified time then rsync
will exit. The default is 0, which means no timeout.

dit(bf(--daemon)) This tells rsync that it is to run as a rsync
daemon. If standard input is a socket then rsync will assume that it
is being run via inetd, otherwise it will detach from the current
terminal and become a background daemon. The daemon will read the
config file (/etc/rsyncd.conf) on each connect made by a client and
respond to requests accordingly. See the rsyncd.conf(5) man page for more
details. 

dit(bf(--config FILE)) This specifies an alternate config file than
the default /etc/rsyncd.conf. This is only relevant when --daemon is
specified. 

dit(bf(--port PORT)) This specifies an alternate TCP port number to use
rather than the default port 873. 

enddit()

manpagefiles()

/etc/rsyncd.conf

manpageseealso()

rsyncd.conf(5)

manpagediagnostics()

manpagebugs()

times are transferred as unix time_t values

file permissions, devices etc are transferred as native numerical
values

see also the comments on the --delete option

Please report bugs! The rsync bug tracking system is online at
url(http://samba.anu.edu.au/rsync/)(http://samba.anu.edu.au/rsync/)

manpagesection(VERSION)
This man page is current for version 2.0 of rsync

manpagesection(CREDITS)

rsync is distributed under the GNU public license.  See the file
COPYING for details.

The primary ftp site for rsync is
url(ftp://samba.anu.edu.au/pub/rsync)(ftp://samba.anu.edu.au/pub/rsync).

A WEB site is available at
url(http://samba.anu.edu.au/rsync/)(http://samba.anu.edu.au/rsync/)

We would be delighted to hear from you if you like this program.

This program uses the zlib compression library written by Jean-loup
Gailly and Mark Adler.

manpagesection(THANKS)

Thanks to Richard Brent, Brendan Mackay, Bill Waite, Stephen Rothwell
and David Bell for helpful suggestions and testing of rsync. I've
probably missed some people, my apologies if I have.


manpageauthor()

rsync was written by Andrew Tridgell and Paul Mackerras.  They may be
contacted via email at tridge@samba.anu.edu.au and
Paul.Mackerras@cs.anu.edu.au