1CPDUP(1) BSD General Commands Manual CPDUP(1)
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4 cpdup — mirror filesystems
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7 cpdup [-C] [-v[v[v]]] [-d] [-n] [-u] [-I] [-f] [-F ssh-arg] [-s0] [-i0]
8 [-j0] [-l] [-q] [-o] [-m] [-H path] [-M file] [-V] [-VV] [-S] [-R]
9 [-k] [-K file] [-X file] [-x] [[user@]host:]source_dir
10 [[user@]host:]target_dir
11
13 The cpdup utility makes an exact mirror copy of the source in the desti‐
14 nation, creating and deleting files and directories as necessary.
15 UTimes, hardlinks, softlinks, devices, permissions, and flags are mir‐
16 rored. By default, cpdup asks for confirmation if any file or directory
17 needs to be removed from the destination and does not copy files which it
18 believes to have already been synchronized (by observing that the source
19 and destination files' sizes and mtimes match). cpdup does not cross
20 mount points in either the source or the destination. As a safety mea‐
21 sure, cpdup refuses to replace a destination directory with a file.
22 The following options are available:
24 -C If the source or target is a remote host, request that the ssh(1)
26 session be compressed. This is the same as -F -C.
27 -v[v[v]]
29 Set verboseness. By default cpdup does not report its progress
30 except when asking for confirmation. A single -v will only report
31 modifications made to the destination. -vv will report directories
32 as they are being traversed as well as modifications made to the
33 destination. -vvv will cause all files and directories to be
34 reported whether or not modifications are made.
35 -d Print directories as they are being traversed. Useful to watch the
37 progress; this typically produces much less output than -vv.
38 -n Go through the motions but don't actually make any changes to the
40 target.
41 -u Causes the output generated by -v and -d to be unbuffered. This
43 can be useful for obtaining prompt progress updates through a pipe.
44 -I will cause cpdup to print a summary at the end with performance
46 counters.
47 -f Forces file updates to occur even if the files appear to be the
49 same. If the -H option is used, this option will force a byte for
50 byte comparison between the original file and the file in the
51 hardlink path, even if all the stat info matches, but will still
52 use a hardlink if they match.
53 -F ssh-arg
55 Pass ssh-arg to ssh. For example “-F -p222”. Note the lack of a
56 space.
57 -s0 Disable the disallow-file-replaces-directory safety feature. This
59 safety feature is enabled by default to prevent user mistakes from
60 blowing away everything accidentally.
61 -i0 Do not request confirmation when removing something.
63 -j0 Do not try to recreate CHR or BLK devices.
65 -l Line buffer verbose output.
67 -q Quiet operation.
69 -o Do not remove any files, just overwrite/add.
71 -m Generate and maintain a MD5 checkfile called .MD5.CHECKSUMS in each
73 directory on the source and do an MD5 check on each file of the
74 destination when the destination appears to be the same as the
75 source. If the check fails, the source is recopied to the destina‐
76 tion. When you specify a destination directory, the MD5 checkfile
77 is only updated as needed and may not be updated even if modifica‐
78 tions are made to a source file. If you do not specify a destina‐
79 tion directory the cpdup command forcefully regenerates the MD5
80 checkfile for every file in the source.
81 -M file
83 Works the same as -m but allows you to specify the name of the MD5
84 checkfile.
85 -H path
87 cpdup will create a hardlink from a file found under path to the
88 target instead of copying the source to the target if the file
89 found via path is identical to the source. Note that a remote host
90 specification should not be used for this option's path, but the
91 path will be relative to the target machine.
92 This allows one to use cpdup to create incremental backups of a
94 filesystem. Create a direct ‘level 0’ backup, and then specify the
95 level 0 backup path with this option when creating an incremental
96 backup to a different target directory. This method works so long
97 as the filesystem does not hit a hardlink limit. If the system
98 does hit a hardlink limit, cpdup will generate a warning and copy
99 the file instead. Note that cpdup must record file paths for any
100 hardlinked file while operating and therefore uses a great deal
101 more memory when dealing with hardlinks or hardlink-based backups.
102 Example use:
103 cpdup -i0 -s0 -I -H /backup/home.l0 /home /backup/home.l1
105 WARNING: If this option is used cpdup must record the paths for all
107 files it encounters while it operates and it is possible that you
108 may run the process out of memory.
109 The file found via the hardlink path will be byte-by-byte compared
111 with the source if the -V or -f option is also used, otherwise only
112 the stat info is checked to determine whether it matches the
113 source.
114 -V This forces the contents of regular files to be verified, even if
116 the files appear to the be the same. Whereas the -f (force) option
117 forces a copy regardless, this option will avoid rewriting the tar‐
118 get if everything matches and the contents are verified to be the
119 same.
120 -VV This works the same as -V but ignores mtime entirely, making it
122 suitable for comparing HAMMER master and slave filesystems or
123 copies made without mtime retention.
124 -S This places cpdup into slave mode and is used to initiate the slave
126 protocol on a remote machine. This option is not intended to be
127 used by humans.
128 -R Place the slave into read-only mode. Can only be used when the
130 source is remote. Useful for unattended backups via SSH keys.
131 -k Generate and maintain a FSMID checkfile called .FSMID.CHECK in
133 each directory on the target. cpdup will check the FSMID for each
134 source file or directory against the checkfile on the target and
135 will not copy the file or recurse through the directory when a
136 match occurs. Any source file or directory with the same name as
137 the checkfile will be ignored. The FSMID will be re-checked after
138 the copy has been completed and cpdup will loop on that directory
139 or file until it is sure it has an exact copy.
140 Warning: FSMID is not always supported by a filesystem and may not
142 be synchronized if a crash occurs. DragonFly will simulate an
143 FSMID when it is otherwise not supported by the filesystem, and
144 users should be aware that simulated FSMIDs may change state in
145 such cases even if the underlying hierarchy does not due to cache
146 flushes. Additionally, the FSMID may not reflect changes made to
147 remote filesystems by other hosts. For example, using these
148 options with NFS mounted sources will not work well.
149 -K file
151 Works the same as -k but allows you to specify the name of the
152 FSMID checkfile.
153 -x Causes cpdup to use the exclusion file .cpignore in each directory
155 on the source to determine which files to ignore. When this option
156 is used, the exclusion filename itself is automatically excluded
157 from the copy. If this option is not used then the filename
158 .cpignore is not considered special and will be copied along with
159 everything else.
160 -X file
162 Works the same as -x but allows you to specify the name of the
163 exclusion file. This file is automatically excluded from the copy.
164 Only one exclusion file may be specified.
165
167 cpdup can mirror directory structures across machines and can also do
168 third-party copies. This also works between machines that use different
169 byte order. ssh(1) sessions are used and cpdup is run on the remote
170 machine(s) in slave mode. You can use the -F option to pass additional
171 flags to the ssh command if necessary.
172 The syntax of remote path specifications is similar to scp(1). In par‐
174 ticular, that means that a local path containing a colon must be preceded
175 by a slash to prevent it being considered a remote host: ‘foo:bar’ causes
176 cpdup to look for a directory called ‘bar’ on host ‘foo’, while
177 ‘./foo:bar’ denotes the directory ‘foo:bar’ on the local machine.
178
180 The cpdup utility exits 0 if no error occurred and >0 if an error
181 occurred.
182
184 cp(1), cpio(1), scp(1), ssh(1), tar(1)
185
187 The cpdup command was originally created to update servers at BEST Inter‐
188 net circa 1997 and was placed under the FreeBSD copyright for inclusion
189 in the ports area in 1999. The program was written by Matthew Dillon,
190 Dima Ruban, and later significantly improved by Oliver Fromme.
191
193 UFS(5) has a hardlink limit of 32767. Many programs, in particular CVS
194 with regards to its CVS/Root file, will generate a lot of hard links.
195 When using the -H option it may not be possible for cpdup to maintain
196 these hard links. If this occurs, cpdup will be forced to copy the file
197 instead of link it, and thus not be able to make a perfect copy of the
198 filesystem.
199 When so-called sparse files (i.e. files with "holes") are copied, the
201 holes will be filled in the target files, so they occupy more physical
202 disk space than the source files.
203 For compatibility reasons, the slave protocol is not as efficient for
205 writing remote files as it is for reading them. Therefore it is recom‐
206 mended to run cpdup on the target machine when making remote copies, so
207 the source machine is remote. If you do it the other way, cpdup will run
208 somewhat slower.
209BSD November 24, 2009 BSD