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
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:
support for copying links, devices, owners, groups and permissions
exclude and exclude-from options similar to GNU tar
a CVS exclude mode for ignoring the same files that CVS would ignore
can use any transparent remote shell, including rsh or ssh
does not require root privileges
pipelining of file transfers to minimize latency costs
support for anonymous or authenticated rsync servers (ideal for
There are six different ways of using rsync. They are:
for copying local files. This is invoked when neither
source nor destination path contains a : separator
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.
for copying from a remote machine to the local machine
using a remote shell program. This is invoked when the source
contains a : separator.
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.
for copying from the local machine to a remote rsync
server. This is invoked when the destination path contains a ::
for listing files on a remote machine. This is done the
same way as rsync transfers except that you leave off the
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
Note that rsync must be installed on both the source and destination
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
differences. 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 "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.
rsync -avz foo:src/bar/ /data/tmp
a trailing slash on the source changes this behavior to transfer
all files from the directory 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 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.
this would list all the anonymous rsync modules available on the host
somehost.mydomain.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
you use a double colon :: instead of a single colon to
separate the hostname from the path.
the remote server may print a message of the day when you
if you specify no path name on the remote server then the
list of accessible paths on the server will be shown.
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 environment 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
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
rsync -Cavz . arvidsjaur:backup
each night over a PPP link to a duplicate directory on my machine
To synchronize my samba source trees I use the following Makefile
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
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 variants, 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; whitespace
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 useful when invoking rsync from
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
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
transferring to/from FAT filesystems which cannot represent times with
a 1 second resolution 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
Note however that -adoes not preserve hardlinks, because
finding multiply-linked files is expensive. You must separately
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 option.
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
When symlinks are encountered, recreate the
symlink on the destination.
When symlinks are encountered, the file that
they point to is copied, rather than the symlink.
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
This option causes rsync to update the remote
permissions to be the same as the local permissions.
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 id
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.
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
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 destination.
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 the files.
This tells rsync not to cross filesystem
boundaries when recursing. This is useful 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
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 sending 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 for details.
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
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 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 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.
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 information.
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.
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 temporary 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 useful 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 destination directory.
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 instead.
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.
This tells rsync that it is to run as a daemon. The
daemon may be accessed using the host::module or
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
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
daemontools 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
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
This specifies an alternate TCP port number to use
rather than the default port 873.
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 blocking 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
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
This tells rsync to print a verbose set of statistics
on the file transfer, allowing 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 transferred 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.
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
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 subcomponent.
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 --exclude options.
The patterns can take several forms. The rules are:
if the pattern starts with a / then it is matched against the
start of the filename, 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.
if the pattern ends with a / then it will only match a
directory, not a file, link or device.
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.
if the pattern includes a double asterisk "**" then all wildcards in
the pattern will match slashes, otherwise they will stop at slashes.
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.
if the pattern starts with "+ " (a plus followed by a space)
then it is always considered an include pattern, even if specified as
part of an exclude option. The "+ " part is discarded before matching.
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.
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
Here are some exclude/include examples:
--exclude "*.o" would exclude all filenames matching *.o
--exclude "/foo" would exclude a file in the base directory called foo
--exclude "foo/" would exclude any directory called foo
--exclude "/foo/*/bar" would exclude any file called bar two
levels below a base directory called foo
--exclude "/foo/**/bar" would exclude any file called bar two
or more levels below a base directory called foo
--include "*/" --include "*.c" --exclude "*" would include all
directories and C source files
--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 fileset.
The fileset consists of 4 files:
<prefix>.rsync_argvs command-line arguments
<prefix>.rsync_flist rsync internal file metadata
<prefix>.rsync_csums rsync checksums
<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, optionally 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. Multicast 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
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 difference 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
The rsync version used on all destinations should be identical to the
one used on the original destination.
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
Three basic behaviours are possible when rsync encounters a symbolic
link in the source directory.
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 destination. Note that --archive implies
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 destination. 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
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 hostname:port pair.
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 username sent to a rsync server.
The HOME environment variable is used to find the user's
default .cvsignore file.