||FreeBSD General Commands Manual
cpdup utility makes an exact mirror copy of the
source in the destination, creating and deleting files and directories as
necessary. UTimes, hardlinks, softlinks, devices, permissions, and flags are
mirrored. By default,
cpdup asks for confirmation if
any file or directory needs to be removed from the destination and does not
copy files which it believes to have already been synchronized (by observing
that the source and destination files' sizes and mtimes match).
cpdup does not cross mount points in either the source
or the destination. As a safety measure,
to replace a destination directory with a file.
The following options are available:
- If the source or target is a remote host, request that the
session be compressed. This is the same as
- Set verboseness. By default
cpdup does not report
its progress except when asking for confirmation. A single
-v will only report modifications made to the
-vv will report directories as they
are being traversed as well as modifications made to the destination.
-vvv will cause all files and directories to be
reported whether or not modifications are made.
- Print directories as they are being traversed. Useful to watch the
progress; this typically produces much less output than
- Go through the motions but don't actually make any changes to the
- Causes the output generated by
-d to be unbuffered. This can be useful for
obtaining prompt progress updates through a pipe.
- will cause
cpdup to print a summary at the end
with performance counters.
- Forces file updates to occur even if the files appear to be the same. If
-H option is used, this option will force a
byte for byte comparison between the original file and the file in the
hardlink path, even if all the stat info matches, but will still use a
hardlink if they match.
- Pass ssh-arg to ssh. For example
Note the lack of a space.
- Disable the disallow-file-replaces-directory safety feature. This safety
feature is enabled by default to prevent user mistakes from blowing away
- Do not request confirmation when removing something.
- Do not try to recreate CHR or BLK devices.
- Line buffer verbose output.
- Quiet operation.
- Do not remove any files, just overwrite/add.
- Generate and maintain a MD5 checkfile called
.MD5.CHECKSUMS in each directory on the source and
do an MD5 check on each file of the destination when the destination
appears to be the same as the source. If the check fails, the source is
recopied to the destination. When you specify a destination directory, the
MD5 checkfile is only updated as needed and may not be updated even if
modifications are made to a source file. If you do not specify a
destination directory the
cpdup command forcefully
regenerates the MD5 checkfile for every file in the source.
- Works the same as
-m but allows you to specify the
name of the MD5 checkfile.
cpdup will create a hardlink from a file found
under path to the target instead of copying the
source to the target if the file found via path is
identical to the source. Note that a remote host specification should not
be used for this option's path, but the
path will be relative to the target machine.
This allows one to use
cpdup to create
incremental backups of a filesystem. Create a direct ‘level
0’ backup, and then specify the level 0 backup path with this
option when creating an incremental backup to a different target
directory. This method works so long as the filesystem does not hit a
hardlink limit. If the system does hit a hardlink limit,
cpdup will generate a warning and copy the file
instead. Note that
cpdup must record file paths
for any hardlinked file while operating and therefore uses a great deal
more memory when dealing with hardlinks or hardlink-based backups.
cpdup -i0 -s0 -I -H
/backup/home.l0 /home /backup/home.l1
WARNING: If this option is used
must record the paths for all files it encounters while it operates and
it is possible that you may run the process out of memory.
The file found via the hardlink path will be byte-by-byte
compared with the source if the
-f option is also used, otherwise only the stat
info is checked to determine whether it matches the source.
- This forces the contents of regular files to be verified, even if the
files appear to the be the same. Whereas the
(force) option forces a copy regardless, this option will avoid rewriting
the target if everything matches and the contents are verified to be the
- This works the same as
-V but ignores mtime
entirely, making it suitable for comparing HAMMER master and slave
filesystems or copies made without mtime retention.
- This places
cpdup into slave mode and is used to
initiate the slave protocol on a remote machine. This option is not
intended to be used by humans.
- Place the slave into read-only mode. Can only be used when the source is
remote. Useful for unattended backups via SSH keys.
cpdup to use the exclusion file
.cpignore in each directory on the source to
determine which files to ignore. When this option is used, the exclusion
filename itself is automatically excluded from the copy. If this option is
not used then the filename .cpignore is not
considered special and will be copied along with everything else.
- Works similarly to
-x but allows you to specify
the name of the exclusion file. This file is automatically excluded from
the copy. Only one exclusion file may be specified.
When an absolute path is used, the same exclusive file is read
for every directory and may contain full paths or wildcarded paths based
on the full source path as specified on the cpdup command line. In this
situation, the exclusive file is read from the host running the command,
NOT from the source host (if remote).
When a relative path is used (or
specified), the exclusion file is only applicable to the directory it
resides in on the source host and only path elements (the directory
elements) are matched against it.
cpdup can mirror directory structures across machines
and can also do third-party copies. This also works between machines that use
different byte order.
sessions are used and
cpdup is run on the remote
machine(s) in slave mode. You can use the
-F option to
pass additional flags to the ssh command if necessary.
The syntax of remote path specifications is similar to
particular, that means that a local path containing a colon must be preceded
by a slash to prevent it being considered a remote host:
cpdup to look for a directory called
bar’ on host
./foo:bar’ denotes the directory
foo:bar’ on the local machine.
cpdup also supports a
localhost:’ prefix which is silently
discarded but prevents any colons in the remainder of the path from being
interpreted as a host:path form. this form can be used with relative
filenames when you do not want colons in the filename to be
cpdup utility exits 0 on success,
and >0 if an error occurs.
cpdup command was originally created to update
servers at BEST Internet circa 1997 and was placed under the
FreeBSD copyright for inclusion in the ports area in
1999. The program was written by Matthew Dillon, Dima Ruban, and later
significantly improved by Oliver Fromme.
UFS(5) has a
hardlink limit of 32767. Many programs, in particular CVS with regards to its
CVS/Root file, will generate a lot of hard links. When using the
-H option it may not be possible for
cpdup to maintain these hard links. If this occurs,
cpdup will be forced to copy the file instead of link
it, and thus not be able to make a perfect copy of the filesystem.
When so-called sparse files (i.e. files with "holes")
are copied, the holes will be filled in the target files, so they occupy
more physical disk space than the source files.
For compatibility reasons, the slave protocol is not as efficient
for writing remote files as it is for reading them. Therefore it is
recommended to run
cpdup on the target machine when
making remote copies, so the source machine is remote. If you do it the
cpdup will run somewhat slower.
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