rsync - faster, flexible replacement for rcp
rsync [OPTION]... SRC [SRC]... [USER@]HOST:DEST
rsync [OPTION]... [USER@]HOST:SRC DEST
rsync [OPTION]... SRC [SRC]... DEST
rsync [OPTION]... [USER@]HOST::SRC [DEST]
rsync [OPTION]... SRC [SRC]... [USER@]HOST::DEST
rsync [OPTION]... rsync://[USER@]HOST[:PORT]/SRC [DEST]
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 speed up 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:
o support for copying links, devices, owners, groups and permissions
o exclude and exclude-from options similar to GNU tar
o a CVS exclude mode for ignoring the same files that CVS would ignore
o can use any transparent remote shell, including rsh or ssh
o does not require root privileges
o pipelining of file transfers to minimize latency costs
o support for anonymous or authenticated rsync servers (ideal for mirroring)
There are six different ways of using rsync. They are:
o for copying local files. This is invoked when neither source nor destination path
contains a : separator
o 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.
o for copying from a remote machine to the local machine using a remote shell pro-
gram. This is invoked when the source contains a : separator.
o for copying from a remote rsync server to the local machine. This is invoked when
the source path contains a :: separator or a rsync:// URL.
o for copying from the local machine to a remote rsync server. This is invoked when
the destination path contains a :: separator.
o for listing files on a remote machine. This is done the same way as rsync transfers
except that you leave off the local destination.
Note that in all cases (other than listing) at least one of the source and destination
paths must be local.
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 an alternative to rsh, either by 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.
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:
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 dif-
ferences. See the tech report for details.
rsync -avz foo:src/bar /data/tmp
this would 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 "ar-
chive" mode, which ensures that symbolic links, devices, attributes, permissions, owner-
ships etc are preserved in the transfer. Additionally, compression will be used to reduce
the size of data portions of the transfer.
rsync -avz foo:src/bar/ /data/tmp
a trailing slash on the source changes this behavior to transfer all files from the direc-
tory src/bar on the machine foo into the /data/tmp/. A trailing / on a source name means
"copy the contents of this directory". Without a trailing slash it means "copy the direc-
tory". 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.
this would list all the anonymous rsync modules available on the host somehost.mydo-
main.com. (See the following section for more details.)
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.
You may establish the connection via a web proxy by setting the environment variable
RSYNC_PROXY to a hostname:port pair pointing to your web proxy. Note that your web
proxy's configuration must allow proxying to port 873.
Using rsync in this way is the same as using it with rsh or ssh except that:
o you use a double colon :: instead of a single colon to separate the hostname from
o the remote server may print a message of the day when you connect.
o if you specify no path name on the remote server then the list of accessible paths
on the server will be shown.
o if you specify no local destination then a listing of the specified files on the
remote server is provided.
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 envi-
ronment variable RSYNC_PASSWORD to the password you want to use or using the --password-
file option. This may be useful when scripting rsync.
WARNING: On some systems environment variables are visible to all users. On those systems
using --password-file is recommended.
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.
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 fold-
ers, I use a cron job that runs
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:
rsync -avuzb --exclude '*~' samba:samba/ .
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
rsync -az -e ssh --delete ~ftp/pub/samba/ nimbus:"~ftp/pub/tridge/samba"
this is launched from cron every few hours.
Here is a short summary of the options available in rsync. Please refer to the detailed
description below for a complete description.
-v, --verbose increase verbosity
-q, --quiet decrease verbosity
-c, --checksum always checksum
-a, --archive archive mode
-r, --recursive recurse into directories
-R, --relative use relative path names
-b, --backup make backups (default ~ suffix)
--backup-dir make backups into this directory
--suffix=SUFFIX override backup suffix
-u, --update update only (don't overwrite newer files)
-l, --links copy symlinks as symlinks
-L, --copy-links copy the referent of symlinks
--copy-unsafe-links copy links outside the source tree
--safe-links ignore links outside the destination tree
-H, --hard-links preserve hard links
-p, --perms preserve permissions
-o, --owner preserve owner (root only)
-g, --group preserve group
-D, --devices preserve devices (root only)
-t, --times preserve times
-S, --sparse handle sparse files efficiently
-n, --dry-run show what would have been transferred
-W, --whole-file copy whole files, no incremental checks
--no-whole-file turn off --whole-file
-x, --one-file-system don't cross filesystem boundaries
-B, --block-size=SIZE checksum blocking size (default 700)
-e, --rsh=COMMAND specify rsh replacement
--rsync-path=PATH specify path to rsync on the remote machine
-C, --cvs-exclude auto ignore files in the same way CVS does
--existing only update files that already exist
--ignore-existing ignore files that already exist on the receiving side
--delete delete files that don't exist on the sending side
--delete-excluded also delete excluded files on the receiving side
--delete-after delete after transferring, not before
--ignore-errors delete even if there are IO errors
--max-delete=NUM don't delete more than NUM files
--partial keep partially transferred files
--force force deletion of directories even if not empty
--numeric-ids don't map uid/gid values by user/group name
--timeout=TIME set IO timeout in seconds
-I, --ignore-times don't exclude files that match length and time
--size-only only use file size when determining if a file should be transferred
--modify-window=NUM Timestamp window (seconds) for file match (default=0)
-T --temp-dir=DIR create temporary files in directory DIR
--compare-dest=DIR also compare destination files relative to DIR
-P equivalent to --partial --progress
-z, --compress compress file data
--exclude=PATTERN exclude files matching PATTERN
--exclude-from=FILE exclude patterns listed in FILE
--include=PATTERN don't exclude files matching PATTERN
--include-from=FILE don't exclude patterns listed in FILE
--version print version number
--daemon run as a rsync daemon
--no-detach do not detach from the parent
--address=ADDRESS bind to the specified address
--config=FILE specify alternate rsyncd.conf file
--port=PORT specify alternate rsyncd port number
--blocking-io use blocking IO for the remote shell
--no-blocking-io turn off --blocking-io
--stats give some file transfer stats
--progress show progress during transfer
--log-format=FORMAT log file transfers using specified format
--password-file=FILE get password from FILE
--bwlimit=KBPS limit I/O bandwidth, KBytes per second
--read-batch=PREFIX read batch fileset starting with PREFIX
--write-batch=PREFIX write batch fileset starting with PREFIX
-h, --help show this help screen
rsync uses the GNU long options package. Many of the command line options have two vari-
ants, one short and one long. These are shown below, separated by commas. Some options
only have a long variant. The '=' for options that take a parameter is optional; white-
space can be used instead.
Print a short help page describing the options available in rsync
print the rsync version number and exit
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.
This option decreases the amount of information you are given during the transfer,
notably suppressing information messages from the remote server. This flag is use-
ful when invoking rsync from cron.
Normally rsync will skip any files that are already the same length and have the
same time-stamp. This option turns off this behavior.
Normally rsync will skip any files that are already the same length and have the
same time-stamp. With the --size-only option files will be skipped if they have the
same size, regardless of timestamp. This is useful when starting to use rsync after
using another mirroring system which may not preserve timestamps exactly.
When comparing two timestamps rsync treats the timestamps as being equal if they
are within the value of modify_window. This is normally zero, but you may find it
useful to set this to a larger value in some situations. In particular, when trans-
ferring to/from FAT filesystems which cannot represent times with a 1 second reso-
lution this option is useful.
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.
This is equivalent to -rlptgoD. It is a quick way of saying you want recursion and
want to preserve almost everything.
Note however that -a does not preserve hardlinks, because finding multiply-linked
files is expensive. You must separately specify -H.
This tells rsync to copy directories recursively. If you don't specify this then
rsync won't copy directories at all.
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 send several different directories at the
same time. For example, if you used the command
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
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.
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
In combination with the --backup option, this tells rsync to store all backups in
the specified directory. This is very useful for incremental backups.
This option allows you to override the default backup suffix used with the -b
option. The default is a ~.
This forces rsync to skip any files for which the destination file already exists
and has a date later than the source file.
When symlinks are encountered, recreate the symlink on the destination.
When symlinks are encountered, the file that they point to is copied, rather than
This tells rsync to copy the referent of symbolic links that point outside the
source tree. Absolute symlinks are also treated like ordinary files, and so are
any symlinks in the source path itself when --relative is used.
This tells rsync to ignore any symbolic links which point outside the destination
tree. All absolute symlinks are also ignored. Using this option in conjunction with
--relative may give unexpected results.
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.
With this option the incremental rsync algorithm is not used and the whole file is
sent as-is instead. The transfer may be faster if this option is used when the
bandwidth between the source and target machines is higher than the bandwidth to
disk (especially when the "disk" is actually a networked file system). This is the
default when both the source and target are on the local machine.
Turn off --whole-file, for use when it is the default.
This option causes rsync to update the remote permissions to be the same as the
This option causes rsync to set the owner of the destination file to be the same as
the source file. On most systems, only the super-user can set file ownership.
This option causes rsync to set the group of the destination file to be the same as
the source file. If the receiving program is not running as the super-user, only
groups that the receiver is a member of will be preserved (by group name, not group
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
This tells rsync to transfer modification times along with the files and update
them on the remote system. Note that if this option is not used, the optimization
that excludes files that have not been modified cannot be effective; in other
words, a missing -t or -a will cause the next transfer to behave as if it used -I,
and all files will have their checksums compared and show up in log messages even
if they haven't changed.
This tells rsync to not do any file transfers, instead it will just report the
actions it would have taken.
Try to handle sparse files efficiently so they take up less space on the destina-
NOTE: Don't use this option when the destination is a Solaris "tmpfs" filesystem.
It doesn't seem to handle seeks over null regions correctly and ends up corrupting
This tells rsync not to cross filesystem boundaries when recursing. This is use-
ful for transferring the contents of only one filesystem.
This tells rsync not to create any new files - only update files that already exist
on the destination.
This tells rsync not to update files that already exist on the destination.
This tells rsync not to delete more than NUM files or directories. This is useful
when mirroring very large trees to prevent disasters.
This tells rsync to delete any files on the receiving side that aren't on the send-
ing side. Files that are excluded from transfer are excluded from being deleted
unless you use --delete-excluded.
This option has no effect if directory recursion is not selected.
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.
If the sending side detects any IO errors then the deletion of any files at the
destination will be automatically disabled. This is to prevent temporary filesystem
failures (such as NFS errors) on the sending side causing a massive deletion of
files on the destination. You can override this with the --ignore-errors option.
In addition to deleting the files on the receiving side that are not on the sending
side, this tells rsync to also delete any files on the receiving side that are
excluded (see --exclude).
By default rsync does file deletions before transferring files to try to ensure
that there is sufficient space on the receiving filesystem. If you want to delete
after transferring then use the --delete-after switch.
Tells --delete to go ahead and delete files even when there are IO errors.
This options tells rsync to delete directories even if they are not empty when they
are to be replaced by non-directories. This is only relevant without --delete
because deletions are now done depth-first. Requires the --recursive option (which
is implied by -a) to have any effect.
-B , --block-size=BLOCKSIZE
This controls the block size used in the rsync algorithm. See the technical report
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 vari-
See also the --blocking-io option which is affected by this option.
Use this to specify the path to the copy of rsync on the remote machine. Useful
when it's not in your path. Note that this is the full path to the binary, not just
the directory that the binary is in.
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.
You may use as many --exclude options on the command line as you like to build up
the list of files to exclude.
See the section on exclude patterns for information on the syntax of this option.
This option is similar to the --exclude option, but instead it adds all exclude
patterns listed in the file FILE to the exclude list. Blank lines in FILE and
lines starting with ';' or '#' are ignored.
This option tells rsync to not exclude the specified pattern of filenames. This is
useful as it allows you to build up quite complex exclude/include rules.
See the section of exclude patterns for information on the syntax of this option.
This specifies a list of include patterns from a file.
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:
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, any file is ignored if it is in the same directory as a .cvsignore file
and matches one of the patterns listed therein. See the cvs(1) manual for more
By default the primary checksum used in rsync is a very strong 16 byte MD4 check-
sum. 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 incor-
rect 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.
Current versions of rsync actually use an adaptive algorithm for the checksum
length by default, using a 16 byte file checksum to determine if a 2nd pass is
required with a longer block checksum. Only use this option if you have read the
source code and know what you are doing.
This option instructs rsync to use DIR as a scratch directory when creating tempo-
rary copies of the files transferred on the receiving side. The default behavior
is to create the temporary files in the receiving directory.
This option instructs rsync to use DIR on the destination machine as an additional
directory to compare destination files against when doing transfers. This is use-
ful for doing transfers to a new destination while leaving existing files intact,
and then doing a flash-cutover when all files have been successfully transferred
(for example by moving directories around and removing the old directory, although
this requires also doing the transfer with -I to avoid skipping files that haven't
changed). This option increases the usefulness of --partial because partially
transferred files will remain in the new temporary destination until they have a
chance to be completed. If DIR is a relative path, it is relative to the destina-
With this option, rsync compresses any data from the files that 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.
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 are never mapped via
user/group names even if the --numeric-ids option is not specified.
If the source system is a daemon using chroot, or if a user or group name does not
exist on the destination system, then the numeric id from the source system is used
This option allows you to set a maximum IO timeout in seconds. If no data is trans-
ferred for the specified time then rsync will exit. The default is 0, which means
This tells rsync that it is to run as a daemon. The daemon may be accessed using
the host::module or rsync://host/module/ syntax.
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.
When running as a daemon, this option instructs rsync to not detach itself and
become a background process. This option is required when running as a service on
Cygwin, and may also be useful when rsync is supervised by a program such as dae-
montools or AIX's System Resource Controller. --no-detach is also recommended when
rsync is run under a debugger. This option has no effect if rsync is run from
inetd or sshd.
By default rsync will bind to the wildcard address when run as a daemon with the
--daemon option or when connecting to a rsync server. The --address option allows
you to specify a specific IP address (or hostname) to bind to. This makes virtual
hosting possible in conjunction with the --config option.
This specifies an alternate config file than the default /etc/rsyncd.conf. This is
only relevant when --daemon is specified.
This specifies an alternate TCP port number to use rather than the default port
This tells rsync to use blocking IO when launching a remote shell transport. If -e
or --rsh are not specified or are set to the default "rsh", this defaults to block-
ing IO, otherwise it defaults to non-blocking IO. You may find the --blocking-io
option is needed for some remote shells that can't handle non-blocking IO. Ssh
prefers blocking IO.
Turn off --blocking-io, for use when it is the default.
This allows you to specify exactly what the rsync client logs to stdout on a per-
file basis. The log format is specified using the same format conventions as the
log format option in rsyncd.conf.
This tells rsync to print a verbose set of statistics on the file transfer, allow-
ing you to tell how effective the rsync algorithm is for your data.
By default, rsync will delete any partially transferred file if the transfer is
interrupted. In some circumstances it is more desirable to keep partially trans-
ferred files. Using the --partial option tells rsync to keep the partial file which
should make a subsequent transfer of the rest of the file much faster.
This option tells rsync to print information showing the progress of the transfer.
This gives a bored user something to watch.
This option is normally combined with -v. Using this option without the -v option
will produce weird results on your display.
-P The -P option is equivalent to --partial --progress. I found myself typing that
combination quite often so I created an option to make it easier.
This option allows you to provide a password in a file for accessing a remote rsync
server. Note that this option is only useful when accessing a rsync server using
the built in transport, not when using a remote shell as the transport. The file
must not be world readable. It should contain just the password as a single line.
This option allows you to specify a maximum transfer rate in kilobytes per second.
This option is most effective when using rsync with large files (several megabytes
and up). Due to the nature of rsync transfers, blocks of data are sent, then if
rsync determines the transfer was too fast, it will wait before sending the next
data block. The result is an average transfer rate equalling the specified limit. A
value of zero specifies no limit.
Generate a set of files that can be transferred as a batch update. Each filename in
the set starts with PREFIX. See the "BATCH MODE" section for details.
Apply a previously generated change batch, using the fileset whose filenames start
with PREFIX. See the "BATCH MODE" section for details.
The exclude and include patterns specified to rsync allow for flexible selection of which
files to transfer and which files to skip.
rsync builds an ordered list of include/exclude options as specified on the command line.
When a filename is encountered, rsync checks the name against each exclude/include pattern
in turn. The first matching pattern is acted on. If it is an exclude pattern, then that
file is skipped. If it is an include pattern then that filename is not skipped. If no
matching include/exclude pattern is found then the filename is not skipped.
Note that when used with -r (which is implied by -a), every subcomponent of every path is
visited from top down, so include/exclude patterns get applied recursively to each subcom-
Note also that the --include and --exclude options take one pattern each. To add multiple
patterns use the --include-from and --exclude-from options or multiple --include and
The patterns can take several forms. The rules are:
o if the pattern starts with a / then it is matched against the start of the file-
name, otherwise it is matched against the end of the filename. Thus "/foo" would
match a file called "foo" at the base of the tree. On the other hand, "foo" would
match any file called "foo" anywhere in the tree because the algorithm is applied
recursively from top down; it behaves as if each path component gets a turn at
being the end of the file name.
o if the pattern ends with a / then it will only match a directory, not a file, link
o if the pattern contains a wildcard character from the set *?[ then expression
matching is applied using the shell filename matching rules. Otherwise a simple
string match is used.
o if the pattern includes a double asterisk "**" then all wildcards in the pattern
will match slashes, otherwise they will stop at slashes.
o if the pattern contains a / (not counting a trailing /) then it is matched against
the full filename, including any leading directory. If the pattern doesn't contain
a / then it is matched only against the final component of the filename. Again,
remember that the algorithm is applied recursively so "full filename" can actually
be any portion of a path.
o if the pattern starts with "+ " (a plus followed by a space) then it is always con-
sidered an include pattern, even if specified as part of an exclude option. The "+
" part is discarded before matching.
o if the pattern starts with "- " (a minus followed by a space) then it is always
considered an exclude pattern, even if specified as part of an include option. The
"- " part is discarded before matching.
o if the pattern is a single exclamation mark ! then the current include/exclude list
is reset, removing all previously defined patterns.
The +/- rules are most useful in exclude lists, allowing you to have a single exclude list
that contains both include and exclude options.
If you end an exclude list with --exclude '*', note that since the algorithm is applied
recursively that unless you explicitly include parent directories of files you want to
include then the algorithm will stop at the parent directories and never see the files
below them. To include all directories, use --include '*/' before the --exclude '*'.
Here are some exclude/include examples:
o --exclude "*.o" would exclude all filenames matching *.o
o --exclude "/foo" would exclude a file in the base directory called foo
o --exclude "foo/" would exclude any directory called foo
o --exclude "/foo/*/bar" would exclude any file called bar two levels below a base
directory called foo
o --exclude "/foo/**/bar" would exclude any file called bar two or more levels below
a base directory called foo
o --include "*/" --include "*.c" --exclude "*" would include all directories and C
o --include "foo/" --include "foo/bar.c" --exclude "*" would include only foo/bar.c
(the foo/ directory must be explicitly included or it would be excluded by the "*")
Note: Batch mode should be considered experimental in this version of rsync. The interface
or behaviour may change before it stabilizes.
Batch mode can be used to apply the same set of updates to many identical systems. Suppose
one has a tree which is replicated on a number of hosts. Now suppose some changes have
been made to this source tree and those changes need to be propagated to the other hosts.
In order to do this using batch mode, rsync is run with the write-batch option to apply
the changes made to the source tree to one of the destination trees. The write-batch
option causes the rsync client to store the information needed to repeat this operation
against other destination trees in a batch update fileset (see below). The filename of
each file in the fileset starts with a prefix specified by the user as an argument to the
write-batch option. This fileset is then copied to each remote host, where rsync is run
with the read-batch option, again specifying the same prefix, and the destination tree.
Rsync updates the destination tree using the information stored in the batch update file-
The fileset consists of 4 files:
o <prefix>.rsync_argvs command-line arguments
o <prefix>.rsync_flist rsync internal file metadata
o <prefix>.rsync_csums rsync checksums
o <prefix>.rsync_delta data blocks for file update & change
The .rsync_argvs file contains a command-line suitable for updating a destination tree
using that batch update fileset. It can be executed using a Bourne(-like) shell, option-
ally passing in an alternate destination tree pathname which is then used instead of the
original path. This is useful when the destination tree path differs from the original
destination tree path.
Generating the batch update fileset once saves having to perform the file status, checksum
and data block generation more than once when updating multiple destination trees. Multi-
cast transport protocols can be used to transfer the batch update files in parallel to
many hosts at once, instead of sending the same data to every host individually.
$ rsync --write_batch=pfx -a /source/dir/ /adest/dir/
$ rcp pfx.rsync_* remote:
$ rsh remote rsync --read_batch=pfx -a /bdest/dir/
# or alternatively
$ rsh remote ./pfx.rsync_argvs /bdest/dir/
In this example, rsync is used to update /adest/dir/ with /source/dir/ and the information
to repeat this operation is stored in the files pfx.rsync_*. These files are then copied
to the machine named "remote". Rsync is then invoked on "remote" to update /bdest/dir/
the same way as /adest/dir/. The last line shows the rsync_argvs file being used to invoke
The read-batch option expects the destination tree it is meant to update to be identical
to the destination tree that was used to create the batch update fileset. When a differ-
ence between the destination trees is encountered the update will fail at that point,
leaving the destination tree in a partially updated state. In that case, rsync can be used
in its regular (non-batch) mode of operation to fix up the destination tree.
The rsync version used on all destinations should be identical to the one used on the
The -z/--compress option does not work in batch mode and yields a usage error. A separate
compression tool can be used instead to reduce the size of the batch update files for
transport to the destination.
The -n/--dryrun option does not work in batch mode and yields a runtime error.
See http://www.ils.unc.edu/i2dsi/unc_rsync+.html for papers and technical reports.
Three basic behaviours are possible when rsync encounters a symbolic link in the source
By default, symbolic links are not transferred at all. A message "skipping non-regular"
file is emitted for any symlinks that exist.
If --links is specified, then symlinks are recreated with the same target on the destina-
tion. Note that --archive implies --links.
If --copy-links is specified, then symlinks are "collapsed" by copying their referent,
rather than the symlink.
rsync also distinguishes "safe" and "unsafe" symbolic links. An example where this might
be used is a web site mirror that wishes ensure the rsync module they copy does not
include symbolic links to /etc/passwd in the public section of the site. Using --copy-
unsafe-links will cause any links to be copied as the file they point to on the destina-
tion. Using --safe-links will cause unsafe links to be ommitted altogether.
rsync occasionally produces error messages that may seem a little cryptic. The one that
seems to cause the most confusion is "protocol version mismatch - is your shell clean?".
This message is usually caused by your startup scripts or remote shell facility producing
unwanted garbage on the stream that rsync is using for its transport. The way to diagnose
this problem is to run your remote shell like this:
rsh remotehost /bin/true > out.dat
then look at out.dat. If everything is working correctly then out.dat should be a zero
length file. If you are getting the above error from rsync then you will probably find
that out.dat contains some text or data. Look at the contents and try to work out what is
producing it. The most common cause is incorrectly configured shell startup scripts (such
as .cshrc or .profile) that contain output statements for non-interactive logins.
If you are having trouble debugging include and exclude patterns, then try specifying the
-vv option. At this level of verbosity rsync will show why each individual file is
included or excluded.
Syntax or usage error
Errors selecting input/output files, dirs
Requested action not supported: an attempt was made to manipulate 64-bit files on a
platform that cannot support them; or an option was speciifed that is supported by
the client and not by the server.
Error in socket IO
Error in file IO
Error in rsync protocol data stream
Errors with program diagnostics
Error in IPC code
Received SIGUSR1 or SIGINT
Some error returned by waitpid()
Error allocating core memory buffers
Timeout in data send/receive
The CVSIGNORE environment variable supplements any ignore patterns in .cvsignore
files. See the --cvs-exclude option for more details.
The RSYNC_RSH environment variable allows you to override the default shell used as
the transport for rsync. This can be used instead of the -e option.
The RSYNC_PROXY environment variable allows you to redirect your rsync client to
use a web proxy when connecting to a rsync daemon. You should set RSYNC_PROXY to a
Setting RSYNC_PASSWORD to the required password allows you to run authenticated
rsync connections to a rsync daemon without user intervention. Note that this does
not supply a password to a shell transport such as ssh.
USER or LOGNAME
The USER or LOGNAME environment variables are used to determine the default user-
name sent to a rsync server.
HOME The HOME environment variable is used to find the user's default .cvsignore file.
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
This man page is current for version 2.0 of rsync
rsync is distributed under the GNU public license. See the file COPYING for details.
A WEB site is available at http://rsync.samba.org/. The site includes an FAQ-O-Matic
which may cover questions unanswered by this manual page.
The primary ftp site for rsync is ftp://rsync.samba.org/pub/rsync.
We would be delighted to hear from you if you like this program.
This program uses the excellent zlib compression library written by Jean-loup Gailly and
Thanks to Richard Brent, Brendan Mackay, Bill Waite, Stephen Rothwell and David Bell for
helpful suggestions, patches and testing of rsync. I've probably missed some people, my
apologies if I have.
Especial thanks also to: David Dykstra, Jos Backus, Sebastian Krahmer.
rsync was written by Andrew Tridgell <email@example.com> and Paul Mackerras.
rsync is now maintained by Martin Pool <firstname.lastname@example.org>.
Mailing lists for support and development are available at http://lists.samba.org
If you suspect you have found a security vulnerability in rsync, please send it directly
to Martin Pool and Andrew Tridgell. For other enquiries, please use the mailing list.
25 Jan 2002 rsync(1)