rsync

31 Dec 2009

rsync(1)

31 Dec 2009

NAME

rsync - a fast, versatile, remote (and local) file-copying tool

SYNOPSIS

Local:  rsync [OPTION...] SRC... [DEST]

Access via remote shell:
  Pull: rsync [OPTION...] [USER@]HOST:SRC... [DEST]
  Push: rsync [OPTION...] SRC... [USER@]HOST:DEST

Access via rsync daemon:
  Pull: rsync [OPTION...] [USER@]HOST::SRC... [DEST]
        rsync [OPTION...] rsync://[USER@]HOST[:PORT]/SRC... [DEST]
  Push: rsync [OPTION...] SRC... [USER@]HOST::DEST
        rsync [OPTION...] SRC... rsync://[USER@]HOST[:PORT]/DEST

Usages with just one SRC arg and no DEST arg will list the source files instead of copying.

DESCRIPTION

Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It offers a large number of options that control every aspect of its behavior and permit very flexible specification of the set of files to be copied. It is famous for its delta-transfer algorithm, which reduces the amount of data sent over the network by sending only the differences between the source files and the existing files in the destination. Rsync is widely used for backups and mirroring and as an improved copy command for everyday use.

Rsync finds files that need to be transferred using a "quick check" algorithm (by default) that looks for files that have changed in size or in last-modified time. Any changes in the other preserved attributes (as requested by options) are made on the destination file directly when the quick check indicates that the file's data does not need to be updated.

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 ssh or rsh
• does not require super-user privileges
• pipelining of file transfers to minimize latency costs
• support for anonymous or authenticated rsync daemons (ideal for mirroring)

GENERAL

Rsync copies files either to or from a remote host, or locally on the current host (it does not support copying files between two remote hosts).

There are two different ways for rsync to contact a remote system: using a remote-shell program as the transport (such as ssh or rsh) or contacting an rsync daemon directly via TCP. The remote-shell transport is used whenever the source or destination path contains a single colon (:) separator after a host specification. Contacting an rsync daemon directly happens when the source or destination path contains a double colon (::) separator after a host specification, OR when an rsync:// URL is specified (see also the "USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION" section for an exception to this latter rule).

As a special case, if a single source arg is specified without a destination, the files are listed in an output format similar to "ls -l".

As expected, if neither the source or destination path specify a remote host, the copy occurs locally (see also the --list-only option).

Rsync refers to the local side as the "client" and the remote side as the "server". Don't confuse "server" with an rsync daemon -- a daemon is always a server, but a server can be either a daemon or a remote-shell spawned process.

SETUP

See the file README for installation instructions.

Once installed, you can use rsync to any machine that you can access via a remote shell (as well as some that you can access using the rsync daemon-mode protocol). For remote transfers, a modern rsync uses ssh for its communications, but it may have been configured to use a different remote shell by default, such as rsh or remsh.

You can also specify any remote shell you like, either by using the -e command line option, or by setting the RSYNC_RSH environment variable.

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

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 with some examples:

rsync -t *.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 avoid creating an additional directory level at the destination. You can think of a trailing / on a source as meaning "copy the contents of this directory" as opposed to "copy the directory by name", but in both cases the attributes of the containing directory are transferred to the containing directory on the destination. In other words, each of the following commands copies the files in the same way, including their setting of the attributes of /dest/foo:

rsync -av /src/foo /dest
rsync -av /src/foo/ /dest/foo

Note also that host and module references don't require a trailing slash to copy the contents of the default directory. For example, both of these copy the remote directory's contents into "/dest":

rsync -av host: /dest
rsync -av host::module /dest

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.

Finally, you can list all the (listable) modules available from a particular rsync daemon by leaving off the module name:

rsync somehost.mydomain.com::

See the following section for more details.

ADVANCED USAGE

The syntax for requesting multiple files from a remote host is done by specifying additional remote-host args in the same style as the first, or with the hostname omitted. For instance, all these work:

rsync -av host:file1 :file2 host:file{3,4} /dest/
rsync -av host::modname/file{1,2} host::modname/file3 /dest/
rsync -av host::modname/file1 ::modname/file{3,4}

Older versions of rsync required using quoted spaces in the SRC, like these examples:

rsync -av host:'dir1/file1 dir2/file2' /dest
rsync host::'modname/dir1/file1 modname/dir2/file2' /dest

This word-splitting still works (by default) in the latest rsync, but is not as easy to use as the first method.

If you need to transfer a filename that contains whitespace, you can either specify the --protect-args (-s) option, or you'll need to escape the whitespace in a way that the remote shell will understand. For instance:

rsync -av host:'file\ name\ with\ spaces' /dest

CONNECTING TO AN RSYNC DAEMON

It is also possible to use rsync without a remote shell as the transport. In this case you will directly connect to a remote rsync daemon, typically using TCP port 873. (This obviously requires the daemon to be running on the remote system, so refer to the STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS section below for information on that.)

Using rsync in this way is the same as using it with a remote shell except that:

• you either use a double colon :: instead of a single colon to separate the hostname from the path, or you use an rsync:// URL.
• the first word of the "path" is actually a module name.
• the remote daemon may print a message of the day when you connect.
• if you specify no path name on the remote daemon then the list of accessible paths on the daemon will be shown.
• if you specify no local destination then a listing of the specified files on the remote daemon is provided.
• you must not specify the --rsh (-e) option.

An example that copies all the files in a remote module named "src":

    rsync -av host::src /dest

Some modules on the remote daemon may require authentication. If so, 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.

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 support proxy connections to port 873.

You may also establish a daemon connection using a program as a proxy by setting the environment variable RSYNC_CONNECT_PROG to the commands you wish to run in place of making a direct socket connection. The string may contain the escape "%H" to represent the hostname specified in the rsync command (so use "%%" if you need a single "%" in your string). For example:

  export RSYNC_CONNECT_PROG='ssh proxyhost nc %H 873'
  rsync -av targethost1::module/src/ /dest/
  rsync -av rsync:://targethost2/module/src/ /dest/ 

The command specified above uses ssh to run nc (netcat) on a proxyhost, which forwards all data to port 873 (the rsync daemon) on the targethost (%H).

USING RSYNC-DAEMON FEATURES VIA A REMOTE-SHELL CONNECTION

It is sometimes useful to use various features of an rsync daemon (such as named modules) without actually allowing any new socket connections into a system (other than what is already required to allow remote-shell access). Rsync supports connecting to a host using a remote shell and then spawning a single-use "daemon" server that expects to read its config file in the home dir of the remote user. This can be useful if you want to encrypt a daemon-style transfer's data, but since the daemon is started up fresh by the remote user, you may not be able to use features such as chroot or change the uid used by the daemon. (For another way to encrypt a daemon transfer, consider using ssh to tunnel a local port to a remote machine and configure a normal rsync daemon on that remote host to only allow connections from "localhost".)

From the user's perspective, a daemon transfer via a remote-shell connection uses nearly the same command-line syntax as a normal rsync-daemon transfer, with the only exception being that you must explicitly set the remote shell program on the command-line with the --rsh=COMMAND option. (Setting the RSYNC_RSH in the environment will not turn on this functionality.) For example:

    rsync -av --rsh=ssh host::module /dest

If you need to specify a different remote-shell user, keep in mind that the user@ prefix in front of the host is specifying the rsync-user value (for a module that requires user-based authentication). This means that you must give the '-l user' option to ssh when specifying the remote-shell, as in this example that uses the short version of the --rsh option:

    rsync -av -e "ssh -l ssh-user" rsync-user@host::module /dest

The "ssh-user" will be used at the ssh level; the "rsync-user" will be used to log-in to the "module".

STARTING AN RSYNC DAEMON TO ACCEPT CONNECTIONS

In order to connect to an rsync daemon, the remote system needs to have a daemon already running (or it needs to have configured something like inetd to spawn an rsync daemon for incoming connections on a particular port). For full information on how to start a daemon that will handling incoming socket connections, see the rsyncd.conf(5) man page -- that is the config file for the daemon, and it contains the full details for how to run the daemon (including stand-alone and inetd configurations).

If you're using one of the remote-shell transports for the transfer, there is no need to manually start an rsync daemon.

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

rsync -Cavz . arvidsjaur:backup

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

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

    get:
            rsync -avuzb --exclude '*~' samba:samba/ .
    put:
            rsync -Cavuzb . samba:samba/
    sync: get put

this allows me to sync with a CVS directory at the other end of the connection. 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"

This is launched from cron every few hours.

OPTIONS SUMMARY

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                 suppress non-error messages
     --no-motd               suppress daemon-mode MOTD (see caveat)
 -c, --checksum              skip based on checksum, not mod-time & size
 -a, --archive               archive mode; equals -rlptgoD (no -H,-A,-X)
     --no-OPTION             turn off an implied OPTION (e.g. --no-D)
 -r, --recursive             recurse into directories
 -R, --relative              use relative path names
     --no-implied-dirs       don't send implied dirs with --relative
 -b, --backup                make backups (see --suffix & --backup-dir)
     --backup-dir=DIR        make backups into hierarchy based in DIR
     --suffix=SUFFIX         backup suffix (default ~ w/o --backup-dir)
 -u, --update                skip files that are newer on the receiver
     --inplace               update destination files in-place
     --append                append data onto shorter files
     --append-verify         --append w/old data in file checksum
 -d, --dirs                  transfer directories without recursing
 -l, --links                 copy symlinks as symlinks
 -L, --copy-links            transform symlink into referent file/dir
     --copy-unsafe-links     only "unsafe" symlinks are transformed
     --safe-links            ignore symlinks that point outside the tree
 -k, --copy-dirlinks         transform symlink to dir into referent dir
 -K, --keep-dirlinks         treat symlinked dir on receiver as dir
 -H, --hard-links            preserve hard links
 -p, --perms                 preserve permissions
 -E, --executability         preserve executability
     --chmod=CHMOD           affect file and/or directory permissions
 -A, --acls                  preserve ACLs (implies -p)
 -X, --xattrs                preserve extended attributes
 -o, --owner                 preserve owner (super-user only)
 -g, --group                 preserve group
     --devices               preserve device files (super-user only)
     --specials              preserve special files
 -D                          same as --devices --specials
 -t, --times                 preserve modification times
 -O, --omit-dir-times        omit directories from --times
     --super                 receiver attempts super-user activities
     --fake-super            store/recover privileged attrs using xattrs
 -S, --sparse                handle sparse files efficiently
 -n, --dry-run               perform a trial run with no changes made
 -W, --whole-file            copy files whole (w/o delta-xfer algorithm)
 -x, --one-file-system       don't cross filesystem boundaries
 -B, --block-size=SIZE       force a fixed checksum block-size
 -e, --rsh=COMMAND           specify the remote shell to use
     --rsync-path=PROGRAM    specify the rsync to run on remote machine
     --existing              skip creating new files on receiver
     --ignore-existing       skip updating files that exist on receiver
     --remove-source-files   sender removes synchronized files (non-dir)
     --del                   an alias for --delete-during
     --delete                delete extraneous files from dest dirs
     --delete-before         receiver deletes before transfer (default)
     --delete-during         receiver deletes during xfer, not before
     --delete-delay          find deletions during, delete after
     --delete-after          receiver deletes after transfer, not before
     --delete-excluded       also delete excluded files from dest dirs
     --ignore-errors         delete even if there are I/O errors
     --force                 force deletion of dirs even if not empty
     --max-delete=NUM        don't delete more than NUM files
     --max-size=SIZE         don't transfer any file larger than SIZE
     --min-size=SIZE         don't transfer any file smaller than SIZE
     --partial               keep partially transferred files
     --partial-dir=DIR       put a partially transferred file into DIR
     --delay-updates         put all updated files into place at end
 -m, --prune-empty-dirs      prune empty directory chains from file-list
     --numeric-ids           don't map uid/gid values by user/group name
     --timeout=SECONDS       set I/O timeout in seconds
     --contimeout=SECONDS    set daemon connection timeout in seconds
 -I, --ignore-times          don't skip files that match size and time
     --size-only             skip files that match in size
     --modify-window=NUM     compare mod-times with reduced accuracy
 -T, --temp-dir=DIR          create temporary files in directory DIR
 -y, --fuzzy                 find similar file for basis if no dest file
     --compare-dest=DIR      also compare received files relative to DIR
     --copy-dest=DIR         ... and include copies of unchanged files
     --link-dest=DIR         hardlink to files in DIR when unchanged
 -z, --compress              compress file data during the transfer
     --compress-level=NUM    explicitly set compression level
     --skip-compress=LIST    skip compressing files with suffix in LIST
 -C, --cvs-exclude           auto-ignore files in the same way CVS does
 -f, --filter=RULE           add a file-filtering RULE
 -F                          same as --filter='dir-merge /.rsync-filter'
                             repeated: --filter='- .rsync-filter'
     --exclude=PATTERN       exclude files matching PATTERN
     --exclude-from=FILE     read exclude patterns from FILE
     --include=PATTERN       don't exclude files matching PATTERN
     --include-from=FILE     read include patterns from FILE
     --files-from=FILE       read list of source-file names from FILE
 -0, --from0                 all *from/filter files are delimited by 0s
 -s, --protect-args          no space-splitting; wildcard chars only
     --address=ADDRESS       bind address for outgoing socket to daemon
     --port=PORT             specify double-colon alternate port number
     --sockopts=OPTIONS      specify custom TCP options
     --blocking-io           use blocking I/O for the remote shell
     --stats                 give some file-transfer stats
 -8, --8-bit-output          leave high-bit chars unescaped in output
 -h, --human-readable        output numbers in a human-readable format
     --progress              show progress during transfer
 -P                          same as --partial --progress
 -i, --itemize-changes       output a change-summary for all updates
     --out-format=FORMAT     output updates using the specified FORMAT
     --log-file=FILE         log what we're doing to the specified FILE
     --log-file-format=FMT   log updates using the specified FMT
     --password-file=FILE    read daemon-access password from FILE
     --list-only             list the files instead of copying them
     --bwlimit=KBPS          limit I/O bandwidth; KBytes per second
     --write-batch=FILE      write a batched update to FILE
     --only-write-batch=FILE like --write-batch but w/o updating dest
     --read-batch=FILE       read a batched update from FILE
     --protocol=NUM          force an older protocol version to be used
     --iconv=CONVERT_SPEC    request charset conversion of filenames
     --checksum-seed=NUM     set block/file checksum seed (advanced)
 -4, --ipv4                  prefer IPv4
 -6, --ipv6                  prefer IPv6
     --version               print version number
(-h) --help                  show this help (see below for -h comment)

Rsync can also be run as a daemon, in which case the following options are accepted:

     --daemon                run as an rsync daemon
     --address=ADDRESS       bind to the specified address
     --bwlimit=KBPS          limit I/O bandwidth; KBytes per second
     --config=FILE           specify alternate rsyncd.conf file
     --no-detach             do not detach from the parent
     --port=PORT             listen on alternate port number
     --log-file=FILE         override the "log file" setting
     --log-file-format=FMT   override the "log format" setting
     --sockopts=OPTIONS      specify custom TCP options
 -v, --verbose               increase verbosity
 -4, --ipv4                  prefer IPv4
 -6, --ipv6                  prefer IPv6
 -h, --help                  show this help (if used after --daemon)

OPTIONS

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.

 

--help

Print a short help page describing the options available in rsync and exit. For backward-compatibility with older versions of rsync, the help will also be output if you use the -h option without any other args.

 

 

--version

print the rsync version number and exit.

 

 

-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 options will give you information on what files are being skipped and slightly more information at the end. More than two -v options should only be used if you are debugging rsync.

Note that the names of the transferred files that are output are done using a default --out-format of "%n%L", which tells you just the name of the file and, if the item is a link, where it points. At the single -v level of verbosity, this does not mention when a file gets its attributes changed. If you ask for an itemized list of changed attributes (either --itemize-changes or adding "%i" to the --out-format setting), the output (on the client) increases to mention all items that are changed in any way. See the --out-format option for more details.

 

 

-q, --quiet

This option decreases the amount of information you are given during the transfer, notably suppressing information messages from the remote server. This option is useful when invoking rsync from cron.

 

 

--no-motd

This option affects the information that is output by the client at the start of a daemon transfer. This suppresses the message-of-the-day (MOTD) text, but it also affects the list of modules that the daemon sends in response to the "rsync host::" request (due to a limitation in the rsync protocol), so omit this option if you want to request the list of modules from the daemon.

 

 

-I, --ignore-times

Normally rsync will skip any files that are already the same size and have the same modification timestamp. This option turns off this "quick check" behavior, causing all files to be updated.

 

 

--size-only

This modifies rsync's "quick check" algorithm for finding files that need to be transferred, changing it from the default of transferring files with either a changed size or a changed last-modified time to just looking for files that have changed in size. This is useful when starting to use rsync after using another mirroring system which may not preserve timestamps exactly.

 

 

--modify-window

When comparing two timestamps, rsync treats the timestamps as being equal if they differ by no more than the modify-window value. This is normally 0 (for an exact match), but you may find it useful to set this to a larger value in some situations. In particular, when transferring to or from an MS Windows FAT filesystem (which represents times with a 2-second resolution), --modify-window=1 is useful (allowing times to differ by up to 1 second).

 

 

-c, --checksum

This changes the way rsync checks if the files have been changed and are in need of a transfer. Without this option, rsync uses a "quick check" that (by default) checks if each file's size and time of last modification match between the sender and receiver. This option changes this to compare a 128-bit checksum for each file that has a matching size. Generating the checksums means that both sides will expend a lot of disk I/O reading all the data in the files in the transfer (and this is prior to any reading that will be done to transfer changed files), so this can slow things down significantly.

The sending side generates its checksums while it is doing the file-system scan that builds the list of the available files. The receiver generates its checksums when it is scanning for changed files, and will checksum any file that has the same size as the corresponding sender's file: files with either a changed size or a changed checksum are selected for transfer.

Note that rsync always verifies that each transferred file was correctly reconstructed on the receiving side by checking a whole-file checksum that is generated as the file is transferred, but that automatic after-the-transfer verification has nothing to do with this option's before-the-transfer "Does this file need to be updated?" check.

For protocol 30 and beyond (first supported in 3.0.0), the checksum used is MD5. For older protocols, the checksum used is MD4.

 

 

-a, --archive

This is equivalent to -rlptgoD. It is a quick way of saying you want recursion and want to preserve almost everything (with -H being a notable omission). The only exception to the above equivalence is when --files-from is specified, in which case -r is not implied.

Note that -a does not preserve hardlinks, because finding multiply-linked files is expensive. You must separately specify -H.

 

 

--no-OPTION

You may turn off one or more implied options by prefixing the option name with "no-". Not all options may be prefixed with a "no-": only options that are implied by other options (e.g. --no-D, --no-perms) or have different defaults in various circumstances (e.g. --no-whole-file, --no-blocking-io, --no-dirs). You may specify either the short or the long option name after the "no-" prefix (e.g. --no-R is the same as --no-relative).

For example: if you want to use -a (--archive) but don't want -o (--owner), instead of converting -a into -rlptgD, you could specify -a --no-o (or -a --no-owner).

The order of the options is important: if you specify --no-r -a, the -r option would end up being turned on, the opposite of -a --no-r. Note also that the side-effects of the --files-from option are NOT positional, as it affects the default state of several options and slightly changes the meaning of -a (see the --files-from option for more details).

 

 

-r, --recursive

This tells rsync to copy directories recursively. See also --dirs (-d).

Beginning with rsync 3.0.0, the recursive algorithm used is now an incremental scan that uses much less memory than before and begins the transfer after the scanning of the first few directories have been completed. This incremental scan only affects our recursion algorithm, and does not change a non-recursive transfer. It is also only possible when both ends of the transfer are at least version 3.0.0.

Some options require rsync to know the full file list, so these options disable the incremental recursion mode. These include: --delete-before, --delete-after, --prune-empty-dirs, and --delay-updates. Because of this, the default delete mode when you specify --delete is now --delete-during when both ends of the connection are at least 3.0.0 (use --del or --delete-during to request this improved deletion mode explicitly). See also the --delete-delay option that is a better choice than using --delete-after.

Incremental recursion can be disabled using the --no-inc-recursive option or its shorter --no-i-r alias.

 

 

-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 send several different directories at the same time. For example, if you used this command:

 

rsync -av /foo/bar/baz.c remote:/tmp/

... this would create a file named baz.c in /tmp/ on the remote machine. If instead you used

 

rsync -avR /foo/bar/baz.c remote:/tmp/

then a file named /tmp/foo/bar/baz.c would be created on the remote machine, preserving its full path. These extra path elements are called "implied directories" (i.e. the "foo" and the "foo/bar" directories in the above example).

Beginning with rsync 3.0.0, rsync always sends these implied directories as real directories in the file list, even if a path element is really a symlink on the sending side. This prevents some really unexpected behaviors when copying the full path of a file that you didn't realize had a symlink in its path. If you want to duplicate a server-side symlink, include both the symlink via its path, and referent directory via its real path. If you're dealing with an older rsync on the sending side, you may need to use the --no-implied-dirs option.

It is also possible to limit the amount of path information that is sent as implied directories for each path you specify. With a modern rsync on the sending side (beginning with 2.6.7), you can insert a dot and a slash into the source path, like this:

 

rsync -avR /foo/./bar/baz.c remote:/tmp/

That would create /tmp/bar/baz.c on the remote machine. (Note that the dot must be followed by a slash, so "/foo/." would not be abbreviated.) For older rsync versions, you would need to use a chdir to limit the source path. For example, when pushing files:

 

(cd /foo; rsync -avR bar/baz.c remote:/tmp/)

(Note that the parens put the two commands into a sub-shell, so that the "cd" command doesn't remain in effect for future commands.) If you're pulling files from an older rsync, use this idiom (but only for a non-daemon transfer):

 

rsync -avR --rsync-path="cd /foo; rsync" \
remote:bar/baz.c /tmp/

 

 

--no-implied-dirs

This option affects the default behavior of the --relative option. When it is specified, the attributes of the implied directories from the source names are not included in the transfer. This means that the corresponding path elements on the destination system are left unchanged if they exist, and any missing implied directories are created with default attributes. This even allows these implied path elements to have big differences, such as being a symlink to a directory on the receiving side.

For instance, if a command-line arg or a files-from entry told rsync to transfer the file "path/foo/file", the directories "path" and "path/foo" are implied when --relative is used. If "path/foo" is a symlink to "bar" on the destination system, the receiving rsync would ordinarily delete "path/foo", recreate it as a directory, and receive the file into the new directory. With --no-implied-dirs, the receiving rsync updates "path/foo/file" using the existing path elements, which means that the file ends up being created in "path/bar". Another way to accomplish this link preservation is to use the --keep-dirlinks option (which will also affect symlinks to directories in the rest of the transfer).

When pulling files from an rsync older than 3.0.0, you may need to use this option if the sending side has a symlink in the path you request and you wish the implied directories to be transferred as normal directories.

 

 

-b, --backup

With this option, preexisting destination files are renamed as each file is transferred or deleted. You can control where the backup file goes and what (if any) suffix gets appended using the --backup-dir and --suffix options.

Note that if you don't specify --backup-dir, (1) the --omit-dir-times option will be implied, and (2) if --delete is also in effect (without --delete-excluded), rsync will add a "protect" filter-rule for the backup suffix to the end of all your existing excludes (e.g. -f "P *~"). This will prevent previously backed-up files from being deleted. Note that if you are supplying your own filter rules, you may need to manually insert your own exclude/protect rule somewhere higher up in the list so that it has a high enough priority to be effective (e.g., if your rules specify a trailing inclusion/exclusion of '*', the auto-added rule would never be reached).

 

 

--backup-dir=DIR

In combination with the --backup option, this tells rsync to store all backups in the specified directory on the receiving side. This can be used for incremental backups. You can additionally specify a backup suffix using the --suffix option (otherwise the files backed up in the specified directory will keep their original filenames).

 

 

--suffix=SUFFIX

This option allows you to override the default backup suffix used with the --backup (-b) option. The default suffix is a ~ if no --backup-dir was specified, otherwise it is an empty string.

 

 

-u, --update

This forces rsync to skip any files which exist on the destination and have a modified time that is newer than the source file. (If an existing destination file has a modification time equal to the source file's, it will be updated if the sizes are different.)

Note that this does not affect the copying of symlinks or other special files. Also, a difference of file format between the sender and receiver is always considered to be important enough for an update, no matter what date is on the objects. In other words, if the source has a directory where the destination has a file, the transfer would occur regardless of the timestamps.

This option is a transfer rule, not an exclude, so it doesn't affect the data that goes into the file-lists, and thus it doesn't affect deletions. It just limits the files that the receiver requests to be transferred.

 

 

--inplace

This option changes how rsync transfers a file when its data needs to be updated: instead of the default method of creating a new copy of the file and moving it into place when it is complete, rsync instead writes the updated data directly to the destination file.

This has several effects: (1) in-use binaries cannot be updated (either the OS will prevent this from happening, or binaries that attempt to swap-in their data will misbehave or crash), (2) the file's data will be in an inconsistent state during the transfer, (3) a file's data may be left in an inconsistent state after the transfer if the transfer is interrupted or if an update fails, (4) a file that does not have write permissions can not be updated, and (5) the efficiency of rsync's delta-transfer algorithm may be reduced if some data in the destination file is overwritten before it can be copied to a position later in the file (one exception to this is if you combine this option with --backup, since rsync is smart enough to use the backup file as the basis file for the transfer).

WARNING: you should not use this option to update files that are being accessed by others, so be careful when choosing to use this for a copy.

This option is useful for transferring large files with block-based changes or appended data, and also on systems that are disk bound, not network bound.

The option implies --partial (since an interrupted transfer does not delete the file), but conflicts with --partial-dir and --delay-updates. Prior to rsync 2.6.4 --inplace was also incompatible with --compare-dest and --link-dest.

 

 

--append

This causes rsync to update a file by appending data onto the end of the file, which presumes that the data that already exists on the receiving side is identical with the start of the file on the sending side. If a file needs to be transferred and its size on the receiver is the same or longer than the size on the sender, the file is skipped. This does not interfere with the updating of a file's non-content attributes (e.g. permissions, ownership, etc.) when the file does not need to be transferred, nor does it affect the updating of any non-regular files. Implies --inplace, but does not conflict with --sparse (since it is always extending a file's length).

 

 

--append-verify

This works just like the --append option, but the existing data on the receiving side is included in the full-file checksum verification step, which will cause a file to be resent if the final verification step fails (rsync uses a normal, non-appending --inplace transfer for the resend).

Note: prior to rsync 3.0.0, the --append option worked like --append-verify, so if you are interacting with an older rsync (or the transfer is using a protocol prior to 30), specifying either append option will initiate an --append-verify transfer.

 

 

-d, --dirs

Tell the sending side to include any directories that are encountered. Unlike --recursive, a directory's contents are not copied unless the directory name specified is "." or ends with a trailing slash (e.g. ".", "dir/.", "dir/", etc.). Without this option or the --recursive option, rsync will skip all directories it encounters (and output a message to that effect for each one). If you specify both --dirs and --recursive, --recursive takes precedence.

The --dirs option is implied by the --files-from option or the --list-only option (including an implied --list-only usage) if --recursive wasn't specified (so that directories are seen in the listing). Specify --no-dirs (or --no-d) if you want to turn this off.

There is also a backward-compatibility helper option, --old-dirs (or --old-d) that tells rsync to use a hack of "-r --exclude='/*/*'" to get an older rsync to list a single directory without recursing.

 

 

-l, --links

When symlinks are encountered, recreate the symlink on the destination.

 

 

-L, --copy-links

When symlinks are encountered, the item that they point to (the referent) is copied, rather than the symlink. In older versions of rsync, this option also had the side-effect of telling the receiving side to follow symlinks, such as symlinks to directories. In a modern rsync such as this one, you'll need to specify --keep-dirlinks (-K) to get this extra behavior. The only exception is when sending files to an rsync that is too old to understand -K -- in that case, the -L option will still have the side-effect of -K on that older receiving rsync.

 

 

--copy-unsafe-links

This tells rsync to copy the referent of symbolic links that point outside the copied tree. Absolute symlinks are also treated like ordinary files, and so are any symlinks in the source path itself when --relative is used. This option has no additional effect if --copy-links was also specified.

 

 

--safe-links

This tells rsync to ignore any symbolic links which point outside the copied tree. All absolute symlinks are also ignored. Using this option in conjunction with --relative may give unexpected results.

 

 

-k, --copy-dirlinks

This option causes the sending side to treat a symlink to a directory as though it were a real directory. This is useful if you don't want symlinks to non-directories to be affected, as they would be using --copy-links.

Without this option, if the sending side has replaced a directory with a symlink to a directory, the receiving side will delete anything that is in the way of the new symlink, including a directory hierarchy (as long as --force or --delete is in effect).

See also --keep-dirlinks for an analogous option for the receiving side.

 

 

-K, --keep-dirlinks

This option causes the receiving side to treat a symlink to a directory as though it were a real directory, but only if it matches a real directory from the sender. Without this option, the receiver's symlink would be deleted and replaced with a real directory.

For example, suppose you transfer a directory "foo" that contains a file "file", but "foo" is a symlink to directory "bar" on the receiver. Without --keep-dirlinks, the receiver deletes symlink "foo", recreates it as a directory, and receives the file into the new directory. With --keep-dirlinks, the receiver keeps the symlink and "file" ends up in "bar".

One note of caution: if you use --keep-dirlinks, you must trust all the symlinks in the copy! If it is possible for an untrusted user to create their own symlink to any directory, the user could then (on a subsequent copy) replace the symlink with a real directory and affect the content of whatever directory the symlink references. For backup copies, you are better off using something like a bind mount instead of a symlink to modify your receiving hierarchy.

See also --copy-dirlinks for an analogous option for the sending side.

 

 

-H, --hard-links

This tells rsync to look for hard-linked files in the transfer and link together the corresponding files on the receiving side. Without this option, hard-linked files in the transfer are treated as though they were separate files.

When you are updating a non-empty destination, this option only ensures that files that are hard-linked together on the source are hard-linked together on the destination. It does NOT currently endeavor to break already existing hard links on the destination that do not exist between the source files. Note, however, that if one or more extra-linked files have content changes, they will become unlinked when updated (assuming you are not using the --inplace option).

Note that rsync can only detect hard links between files that are inside the transfer set. If rsync updates a file that has extra hard-link connections to files outside the transfer, that linkage will be broken. If you are tempted to use the --inplace option to avoid this breakage, be very careful that you know how your files are being updated so that you are certain that no unintended changes happen due to lingering hard links (and see the --inplace option for more caveats).

If incremental recursion is active (see --recursive), rsync may transfer a missing hard-linked file before it finds that another link for that contents exists elsewhere in the hierarchy. This does not affect the accuracy of the transfer, just its efficiency. One way to avoid this is to disable incremental recursion using the --no-inc-recursive option.

 

 

-p, --perms

This option causes the receiving rsync to set the destination permissions to be the same as the source permissions. (See also the --chmod option for a way to modify what rsync considers to be the source permissions.)

When this option is off, permissions are set as follows:

 

• Existing files (including updated files) retain their existing permissions, though the --executability option might change just the execute permission for the file.
• New files get their "normal" permission bits set to the source file's permissions masked with the receiving directory's default permissions (either the receiving process's umask, or the permissions specified via the destination directory's default ACL), and their special permission bits disabled except in the case where a new directory inherits a setgid bit from its parent directory.

Thus, when --perms and --executability are both disabled, rsync's behavior is the same as that of other file-copy utilities, such as cp(1) and tar(1).

In summary: to give destination files (both old and new) the source permissions, use --perms. To give new files the destination-default permissions (while leaving existing files unchanged), make sure that the --perms option is off and use --chmod=ugo=rwX (which ensures that all non-masked bits get enabled). If you'd care to make this latter behavior easier to type, you could define a popt alias for it, such as putting this line in the file ~/.popt (the following defines the -Z option, and includes --no-g to use the default group of the destination dir):

 

rsync alias -Z --no-p --no-g --chmod=ugo=rwX

You could then use this new option in a command such as this one:

 

rsync -avZ src/ dest/

(Caveat: make sure that -a does not follow -Z, or it will re-enable the two "--no-*" options mentioned above.)

The preservation of the destination's setgid bit on newly-created directories when --perms is off was added in rsync 2.6.7. Older rsync versions erroneously preserved the three special permission bits for newly-created files when --perms was off, while overriding the destination's setgid bit setting on a newly-created directory. Default ACL observance was added to the ACL patch for rsync 2.6.7, so older (or non-ACL-enabled) rsyncs use the umask even if default ACLs are present. (Keep in mind that it is the version of the receiving rsync that affects these behaviors.)

 

 

-E, --executability

This option causes rsync to preserve the executability (or non-executability) of regular files when --perms is not enabled. A regular file is considered to be executable if at least one 'x' is turned on in its permissions. When an existing destination file's executability differs from that of the corresponding source file, rsync modifies the destination file's permissions as follows:

 

• To make a file non-executable, rsync turns off all its 'x' permissions.
• To make a file executable, rsync turns on each 'x' permission that has a corresponding 'r' permission enabled.

If --perms is enabled, this option is ignored.

 

 

-A, --acls

This option causes rsync to update the destination ACLs to be the same as the source ACLs. The option also implies --perms.

The source and destination systems must have compatible ACL entries for this option to work properly. See the --fake-super option for a way to backup and restore ACLs that are not compatible.

 

 

-X, --xattrs

This option causes rsync to update the remote extended attributes to be the same as the local ones.

For systems that support extended-attribute namespaces, a copy being done by a super-user copies all namespaces except system.*. A normal user only copies the user.* namespace. To be able to backup and restore non-user namespaces as a normal user, see the --fake-super option.

 

 

--chmod

This option tells rsync to apply one or more comma-separated "chmod" strings to the permission of the files in the transfer. The resulting value is treated as though it were the permissions that the sending side supplied for the file, which means that this option can seem to have no effect on existing files if --perms is not enabled.

In addition to the normal parsing rules specified in the chmod(1) manpage, you can specify an item that should only apply to a directory by prefixing it with a 'D', or specify an item that should only apply to a file by prefixing it with a 'F'. For example:

 

--chmod=Dg+s,ug+w,Fo-w,+X

It is also legal to specify multiple --chmod options, as each additional option is just appended to the list of changes to make.

See the --perms and --executability options for how the resulting permission value can be applied to the files in the transfer.

 

 

-o, --owner

This option causes rsync to set the owner of the destination file to be the same as the source file, but only if the receiving rsync is being run as the super-user (see also the --super and --fake-super options). Without this option, the owner of new and/or transferred files are set to the invoking user on the receiving side.

The preservation of ownership will associate matching names by default, but may fall back to using the ID number in some circumstances (see also the --numeric-ids option for a full discussion).

 

 

-g, --group

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 (or if --no-super was specified), only groups that the invoking user on the receiving side is a member of will be preserved. Without this option, the group is set to the default group of the invoking user on the receiving side.

The preservation of group information will associate matching names by default, but may fall back to using the ID number in some circumstances (see also the --numeric-ids option for a full discussion).

 

 

--devices

This option causes rsync to transfer character and block device files to the remote system to recreate these devices. This option has no effect if the receiving rsync is not run as the super-user (see also the --super and --fake-super options).

 

 

--specials

This option causes rsync to transfer special files such as named sockets and fifos.

 

 

-D

The -D option is equivalent to --devices --specials.

 

 

-t, --times

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, causing all files to be updated (though rsync's delta-transfer algorithm will make the update fairly efficient if the files haven't actually changed, you're much better off using -t).

 

 

-O, --omit-dir-times

This tells rsync to omit directories when it is preserving modification times (see --times). If NFS is sharing the directories on the receiving side, it is a good idea to use -O. This option is inferred if you use --backup without --backup-dir.

 

 

--super

This tells the receiving side to attempt super-user activities even if the receiving rsync wasn't run by the super-user. These activities include: preserving users via the --owner option, preserving all groups (not just the current user's groups) via the --groups option, and copying devices via the --devices option. This is useful for systems that allow such activities without being the super-user, and also for ensuring that you will get errors if the receiving side isn't being run as the super-user. To turn off super-user activities, the super-user can use --no-super.

 

 

--fake-super

When this option is enabled, rsync simulates super-user activities by saving/restoring the privileged attributes via special extended attributes that are attached to each file (as needed). This includes the file's owner and group (if it is not the default), the file's device info (device & special files are created as empty text files), and any permission bits that we won't allow to be set on the real file (e.g. the real file gets u-s,g-s,o-t for safety) or that would limit the owner's access (since the real super-user can always access/change a file, the files we create can always be accessed/changed by the creating user). This option also handles ACLs (if --acls was specified) and non-user extended attributes (if --xattrs was specified).

This is a good way to backup data without using a super-user, and to store ACLs from incompatible systems.

The --fake-super option only affects the side where the option is used. To affect the remote side of a remote-shell connection, specify an rsync path:

 

rsync -av --rsync-path="rsync --fake-super" /src/ host:/dest/

Since there is only one "side" in a local copy, this option affects both the sending and receiving of files. You'll need to specify a copy using "localhost" if you need to avoid this, possibly using the "lsh" shell script (from the support directory) as a substitute for an actual remote shell (see --rsh).

This option is overridden by both --super and --no-super.

See also the "fake super" setting in the daemon's rsyncd.conf file.

 

 

-S, --sparse

Try to handle sparse files efficiently so they take up less space on the destination. Conflicts with --inplace because it's not possible to overwrite data in a sparse fashion.

NOTE: Don't use this option when the destination is a Solaris "tmpfs" filesystem. It seems to have problems seeking over null regions, and ends up corrupting the files.

 

 

-n, --dry-run

This makes rsync perform a trial run that doesn't make any changes (and produces mostly the same output as a real run). It is most commonly used in combination with the -v, --verbose and/or -i, --itemize-changes options to see what an rsync command is going to do before one actually runs it.

The output of --itemize-changes is supposed to be exactly the same on a dry run and a subsequent real run (barring intentional trickery and system call failures); if it isn't, that's a bug. Other output should be mostly unchanged, but may differ in some areas. Notably, a dry run does not send the actual data for file transfers, so --progress has no effect, the "bytes sent", "bytes received", "literal data", and "matched data" statistics are too small, and the "speedup" value is equivalent to a run where no file transfers were needed.

 

 

-W, --whole-file

With this option rsync's delta-transfer 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 destination machines is higher than the bandwidth to disk (especially when the "disk" is actually a networked filesystem). This is the default when both the source and destination are specified as local paths, but only if no batch-writing option is in effect.

 

 

-x, --one-file-system

This tells rsync to avoid crossing a filesystem boundary when recursing. This does not limit the user's ability to specify items to copy from multiple filesystems, just rsync's recursion through the hierarchy of each directory that the user specified, and also the analogous recursion on the receiving side during deletion. Also keep in mind that rsync treats a "bind" mount to the same device as being on the same filesystem.

If this option is repeated, rsync omits all mount-point directories from the copy. Otherwise, it includes an empty directory at each mount-point it encounters (using the attributes of the mounted directory because those of the underlying mount-point directory are inaccessible).

If rsync has been told to collapse symlinks (via --copy-links or --copy-unsafe-links), a symlink to a directory on another device is treated like a mount-point. Symlinks to non-directories are unaffected by this option.

 

 

--existing, --ignore-non-existing

This tells rsync to skip creating files (including directories) that do not exist yet on the destination. If this option is combined with the --ignore-existing option, no files will be updated (which can be useful if all you want to do is delete extraneous files).

This option is a transfer rule, not an exclude, so it doesn't affect the data that goes into the file-lists, and thus it doesn't affect deletions. It just limits the files that the receiver requests to be transferred.

 

 

--ignore-existing

This tells rsync to skip updating files that already exist on the destination (this does not ignore existing directories, or nothing would get done). See also --existing.

This option is a transfer