-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; same as -rlptgoD (no -H, -A)
+ -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
-E, --executability preserve executability
--chmod=CHMOD affect file and/or directory permissions
-A, --acls preserve ACLs (implies -p)
+ -X, --xattrs preserve extended attrs (implies -p)
-o, --owner preserve owner (super-user only)
-g, --group preserve group
--devices preserve device files (super-user only)
times with a 2-second resolution), bf(--modify-window=1) is useful
(allowing times to differ by up to 1 second).
-dit(bf(-c, --checksum)) This forces the sender to checksum em(every)
-regular file using a 128-bit MD4 checksum. It does this during the initial
-file-system scan as it builds the list of all available files. The receiver
-then checksums its version of each file (if it exists and it has the same
-size as its sender-side counterpart) in order to decide which files need to
-be updated: files with either a changed size or a changed checksum are
-selected for transfer. Since this whole-file checksumming of all files on
-both sides of the connection occurs in addition to the automatic checksum
-verifications that occur during a file's transfer, this option can be quite
-slow.
-
-Note that rsync always verifies that each em(transferred) file was correctly
-reconstructed on the receiving side by checking its whole-file checksum, but
-that automatic after-the-transfer verification has nothing to do with this
+dit(bf(-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 MD4 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 em(transferred) file was
+correctly reconstructed on the receiving side by checking a whole-file
+checksum that is generated when 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.
dit(bf(-a, --archive)) This is equivalent to bf(-rlptgoD). It is a quick
ACLs to be the same as the source ACLs. This nonstandard option only
works if the remote rsync also supports it. bf(--acls) implies bf(--perms).
+dit(bf(-X, --xattrs)) This option causes rsync to update the remote
+extended attributes to be the same as the local ones. This will work
+only if the remote machine's rsync supports this option also. This is
+a non-standard option.
+
dit(bf(--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 was the permissions
Matt McCutchen's Web Site / rsync / rsync.git / blobdiff