SYNOPSIS
rdiff-backup [options] [[[user@]host1.foo]::source_directory]
[[[user@]host2.foo]::destination_directory]
rdiff-backup {{ -l | --list-increments } | --remove-older-than
time_interval | --list-at-time time | --list-changed-since time |
--list-increment-sizes } [[[user@]host2.foo]::destination_directory]
rdiff-backup --calculate-average statfile1 statfile2 ...
rdiff-backup --test-server [user1]@host1.net1::path
[[user2]@host2.net2::path] ...
DESCRIPTION
rdiff-backup is a script, written in python(1) that backs up one direc-
tory to another. The target directory ends up a copy (mirror) of the
source directory, but extra reverse diffs are stored in a special sub-
directory of that target directory, so you can still recover files lost
some time ago. The idea is to combine the best features of a mirror
and an incremental backup. rdiff-backup also preserves symlinks, spe-
cial files, hardlinks, permissions, uid/gid ownership, and modification
times.
rdiff-backup can also operate in a bandwidth efficient manner over a
pipe, like rsync(1). Thus you can use ssh and rdiff-backup to securely
back a hard drive up to a remote location, and only the differences
will be transmitted. Using the default settings, rdiff-backup requires
that the remote system accept ssh connections, and that rdiff-backup is
installed in the user's PATH on the remote system. For information on
other options, see the section on REMOTE OPERATION.
Note that you should not write to the mirror directory except with
rdiff-backup. Many of the increments are stored as reverse diffs, so
if you delete or modify a file, you may lose the ability to restore
previous versions of that file.
Finally, this man page is intended more as a precise description of the
behavior and syntax of rdiff-backup. New users may want to check out
the examples.html file included in the rdiff-backup distribution.
OPTIONS
-b, --backup-mode
Force backup mode even if first argument appears to be an incre-
ment or mirror file.
--calculate-average
Enter calculate average mode. The arguments should be a number
of statistics files. rdiff-backup will print the average of the
listed statistics files and exit.
--create-full-path
Normally only the final directory of the destination path will
be created if it does not exist. With this option, all missing
directories on the destination path will be created. Use this
option with care: if there is a typo in the remote path, the
remote filesystem could fill up very quickly (by creating a
duplicate backup tree). For this reason this option is primarily
aimed at scripts which automate backups.
--current-time seconds
This option is useful mainly for testing. If set, rdiff-backup
will it for the current time instead of consulting the clock.
The argument is the number of seconds since the epoch.
--exclude shell_pattern
Exclude the file or files matched by shell_pattern. If a direc-
tory is matched, then files under that directory will also be
matched. See the FILE SELECTION section for more information.
--exclude-device-files
Exclude all device files. This can be useful for security/per-
missions reasons or if rdiff-backup is not handling device files
correctly.
--exclude-fifos
Exclude all fifo files.
--exclude-filelist filename
Excludes the files listed in filename. If filename is handwrit-
ten you probably want --include-globbing-filelist instead. See
the FILE SELECTION section for more information.
--exclude-filelist-stdin
Like --exclude-filelist, but the list of files will be read from
standard input. See the FILE SELECTION section for more infor-
mation.
--exclude-globbing-filelist filename
Like --exclude-filelist but each line of the filelist will be
interpreted according to the same rules as --include and
--exclude.
--exclude-globbing-filelist-stdin
Like --exclude-globbing-filelist, but the list of files will be
read from standard input.
--exclude-other-filesystems
Exclude files on file systems (identified by device number)
other than the file system the root of the source directory is
on.
--exclude-regexp regexp
--force
Authorize a more drastic modification of a directory than usual
(for instance, when overwriting of a destination path, or when
removing multiple sessions with --remove-older-than). rdiff-
backup will generally tell you if it needs this.
--group-mapping-file filename
Map group names and ids according the the group mapping file
filename. See the USERS AND GROUPS section for more informa-
tion.
--include shell_pattern
Similar to --exclude but include matched files instead. Unlike
--exclude, this option will also match parent directories of
matched files (although not necessarily their contents). See
the FILE SELECTION section for more information.
--include-filelist filename
Like --exclude-filelist, but include the listed files instead.
If filename is handwritten you probably want --exclude-globbing-
filelist instead. See the FILE SELECTION section for more
information.
--include-filelist-stdin
Like --include-filelist, but read the list of included files
from standard input.
--include-globbing-filelist filename
Like --include-filelist but each line of the filelist will be
interpreted according to the same rules as --include and
--exclude.
--include-globbing-filelist-stdin
Like --include-globbing-filelist, but the list of files will be
read from standard input.
--include-regexp regexp
Include files matching the regular expression regexp. Only
files explicitly matched by regexp will be included by this
option. See the FILE SELECTION section for more information.
--include-special-files
Include all device files, fifo files, socket files, and symbolic
links.
--include-symbolic-links
Include all symbolic links.
--list-at-time time
List the files in the archive that were present at the given
time. If a directory in the archive is specified, list only the
files under that directory.
--list-increment-sizes
List the total size of all the increment and mirror files by
time. This may be helpful in deciding how many increments to
keep, and when to --remove-older-than. Specifying a subdirec-
tory is allowable; then only the sizes of the mirror and incre-
ments pertaining to that subdirectory will be listed.
--never-drop-acls
Exit with error instead of dropping acls or acl entries. Nor-
mally this may happen (with a warning) because the destination
does not support them or because the relevant user/group names
do not exist on the destination side.
--no-compare-inode
This relatively esoteric option prevents rdiff-backup from flag-
ging a file as changed when its inode changes. This option may
be useful if you are backing up two different directories to the
same rdiff-backup destination directory. The downside is that
hard link information may get messed up, as the metadata file
may no longer have the correct inode information.
--no-compression
Disable the default gzip compression of most of the .snapshot
and .diff increment files stored in the rdiff-backup-data direc-
tory. A backup volume can contain compressed and uncompressed
increments, so using this option inconsistently is fine.
--no-compression-regexp regexp
Do not compress increments based on files whose filenames match
regexp. The default includes many common audiovisual and ar-
chive files, and may be found in Globals.py.
--no-file-statistics
This will disable writing to the file_statistics file in the
rdiff-backup-data directory. rdiff-backup will run slightly
quicker and take up a bit less space.
--no-hard-links
Don't replicate hard links on destination side. Note that
because metadata is written to a separate file, hard link infor-
mation will not be lost even if the --no-hard-links option is
given (however, mirror files will not be linked). If many hard-
linked files are present, this option can drastically decrease
memory usage.
--null-separator
Use nulls (\0) instead of newlines (\n) as line separators,
which may help when dealing with filenames containing newlines.
This affects the expected format of the files specified by the
--{include|exclude}-filelist[-stdin] switches as well as the
format of the directory statistics file.
Restore the specified directory as it was as of restore_time.
See the TIME FORMATS section for more information on the format
of restore_time, and see the RESTORING section for more informa-
tion on restoring.
--remote-schema schema
Specify an alternate method of connecting to a remote computer.
This is necessary to get rdiff-backup not to use ssh for remote
backups, or if, for instance, rdiff-backup is not in the PATH on
the remote side. See the REMOTE OPERATION section for more
information.
--remove-older-than time_spec
Remove the incremental backup information in the destination
directory that has been around longer than the given time.
time_spec can be either an absolute time, like "2002-01-04", or
a time interval. The time interval is an integer followed by
the character s, m, h, D, W, M, or Y, indicating seconds, min-
utes, hours, days, weeks, months, or years respectively, or a
number of these concatenated. For example, 32m means 32 min-
utes, and 3W2D10h7s means 3 weeks, 2 days, 10 hours, and 7 sec-
onds. In this context, a month means 30 days, a year is 365
days, and a day is always 86400 seconds.
rdiff-backup cannot remove-older-than and back up or restore in
a single session. In order to both backup a directory and
remove old files in it, you must run rdiff-backup twice.
By default, rdiff-backup will only delete information from one
session at a time. To remove two or more sessions at the same
time, supply the --force option (rdiff-backup will tell you if
--force is required).
Note that snapshots of deleted files are covered by this opera-
tion. Thus if you deleted a file two weeks ago, backed up imme-
diately afterwards, and then ran rdiff-backup with --remove-
older-than 10D today, no trace of that file would remain.
Finally, file selection options such as --include and --exclude
don't affect --remove-older-than.
--restrict path
Require that all file access be inside the given path. This
switch, and the following two, are intended to be used with the
--server switch to provide a bit more protection when doing
automated remote backups. They are not intended as your only
line of defense so please don't do something silly like allow
public access to an rdiff-backup server run with --restrict-
read-only.
--restrict-read-only path
Like --restrict, but also reject all write requests.
--terminal-verbosity [0-9]
Select which messages will be displayed to the terminal. If
missing the level defaults to the verbosity level.
--test-server
Test for the presence of a compatible rdiff-backup server as
specified in the following host::filename argument(s). The
filename section will be ignored.
--user-mapping-file filename
Map user names and ids according to the user mapping file file-
name. See the USERS and GROUPS section for more information.
-v[0-9], --verbosity [0-9]
Specify verbosity level (0 is totally silent, 3 is the default,
and 9 is noisiest). This determines how much is written to the
log file.
-V, --version
Print the current version and exit
RESTORING
There are two ways to tell rdiff-backup to restore a file or directory.
Firstly, you can run rdiff-backup on a mirror file and use the -r or
--restore-as-of options. Secondly, you can run it on an increment
file.
For example, suppose in the past you have run:
rdiff-backup /usr /usr.backup
to back up the /usr directory into the /usr.backup directory, and now
want a copy of the /usr/local directory the way it was 3 days ago
placed at /usr/local.old.
One way to do this is to run:
rdiff-backup -r 3D /usr.backup/local /usr/local.old
where above the "3D" means 3 days (for other ways to specify the time,
see the TIME FORMATS section). The /usr.backup/local directory was
selected, because that is the directory containing the current version
of /usr/local.
Note that the option to --restore-as-of always specifies an exact time.
(So "3D" refers to the instant 72 hours before the present.) If there
was no backup made at that time, rdiff-backup restores the state
recorded for the previous backup. For instance, in the above case, if
"3D" is used, and there are only backups from 2 days and 4 days ago,
/usr/local as it was 4 days ago will be restored.
If you are not sure exactly which version of a file you need, it is
probably easiest to either restore from the increments files as
described immediately above, or to see which increments are available
with -l/--list-increments, and then specify exact times into
-r/--restore-as-of.
TIME FORMATS
rdiff-backup uses time strings in two places. Firstly, all of the
increment files rdiff-backup creates will have the time in their file-
names in the w3 datetime format as described in a w3 note at
http://www.w3.org/TR/NOTE-datetime. Basically they look like
"2001-07-15T04:09:38-07:00", which means what it looks like. The
"-07:00" section means the time zone is 7 hours behind UTC.
Secondly, the -r, --restore-as-of, and --remove-older-than options take
a time string, which can be given in any of several formats:
1. the string "now" (refers to the current time)
2. a sequences of digits, like "123456890" (indicating the time in
seconds after the epoch)
3. A string like "2002-01-25T07:00:00+02:00" in datetime format
4. An interval, which is a number followed by one of the characters
s, m, h, D, W, M, or Y (indicating seconds, minutes, hourse,
days, weeks, months, or years respectively), or a series of such
pairs. In this case the string refers to the time that preceded
the current time by the length of the interval. For instance,
"1h78m" indicates the time that was one hour and 78 minutes ago.
The calendar here is unsophisticated: a month is always 30 days,
a year is always 365 days, and a day is always 86400 seconds.
5. A date format of the form YYYY/MM/DD, YYYY-MM-DD, MM/DD/YYYY, or
MM/DD/YYYY, which indicates midnight on the day in question,
relative to the current timezone settings. For instance,
"2002/3/5", "03-05-2002", and "2002-3-05" all mean March 5th,
2002.
6. A backup session specification which is a non-negative integer
followed by 'B'. For instance, '0B' specifies the time of the
current mirror, and '3B' specifies the time of the 3rd newest
increment.
REMOTE OPERATION
In order to access remote files, rdiff-backup opens up a pipe to a copy
of rdiff-backup running on the remote machine. Thus rdiff-backup must
be installed on both ends. To open this pipe, rdiff-backup first
splits the filename into host_info::pathname. It then substitutes
host_info into the remote schema, and runs the resulting command, read-
in the pathname of a local file, you can quote one of them by prepend-
ing a backslash. So in 'a\::b::c', host_info is 'a::b' and the path-
name is 'c'. Similarly, if you want to refer to a local file whose
filename contains two consecutive colons, like 'strange::file', you'll
have to quote one of the colons as in 'strange\::file'. Because the
backslash is a quote character in these circumstances, it too must be
quoted to get a literal backslash, so 'foo\::\\bar' evaluates to
'foo::\bar'. To make things more complicated, because the backslash is
also a common shell quoting character, you may need to type in '\\\\'
at the shell prompt to get a literal backslash (if it makes you feel
better, I had to type in 8 backslashes to get that in this man
page...). And finally, to include a literal % in the string specified
by --remote-schema, quote it with another %, as in %%.
Although ssh itself may be secure, using rdiff-backup in the default
way presents some security risks. For instance if the server is run as
root, then an attacker who compromised the client could then use rdiff-
backup to overwrite arbitary server files by "backing up" over them.
Such a setup can be made more secure by using the sshd configuration
option command="rdiff-backup --server" possibly along with the
--restrict* options to rdiff-backup. For more information, see the web
page, the wiki, and the entries for the --restrict* options on this man
page.
FILE SELECTION
rdiff-backup has a number of file selection options. When rdiff-backup
is run, it searches through the given source directory and backs up all
the files matching the specified options. This selection system may
appear complicated, but it is supposed to be flexible and easy-to-use.
If you just want to learn the basics, first look at the selection exam-
ples in the examples.html file included in the package, or on the web
at http://rdiff-backup.nongnu.org/examples.html
rdiff-backup's selection system was originally inspired by rsync(1),
but there are many differences. (For instance, trailing backslashes
have no special significance.)
The file selection system comprises a number of file selection condi-
tions, which are set using one of the following command line options:
--exclude, --exclude-filelist, --exclude-device-files, --exclude-fifos,
--exclude-sockets, --exclude-symbolic-links, --exclude-globbing-
filelist, --exclude-globbing-filelist-stdin, --exclude-filelist-stdin,
--exclude-regexp, --exclude-special-files, --include, --include-
filelist, --include-globbing-filelist, --include-globbing-filelist-
stdin, --include-filelist-stdin, and --include-regexp. Each file
selection condition either matches or doesn't match a given file. A
given file is excluded by the file selection system exactly when the
first matching file selection condition specifies that the file be
excluded; otherwise the file is included. When backing up, if a file
is excluded, rdiff-backup acts as if that file does not exist in the
source directory. When restoring, an excluded file is considered not
/backup
would backup the /usr/local/bin directory (and its contents), but not
/usr/local/doc.
The include, exclude, include-globbing-filelist, and exclude-globbing-
filelist options accept extended shell globbing patterns. These pat-
terns can contain the special patterns *, **, ?, and [...]. As in a
normal shell, * can be expanded to any string of characters not con-
taining "/", ? expands to any character except "/", and [...] expands
to a single character of those characters specified (ranges are accept-
able). The new special pattern, **, expands to any string of charac-
ters whether or not it contains "/". Furthermore, if the pattern
starts with "ignorecase:" (case insensitive), then this prefix will be
removed and any character in the string can be replaced with an upper-
or lowercase version of itself.
Remember that you may need to quote these characters when typing them
into a shell, so the shell does not interpret the globbing patterns
before rdiff-backup sees them.
The --exclude pattern option matches a file iff:
1. pattern can be expanded into the file's filename, or
2. the file is inside a directory matched by the option.
Conversely, --include pattern matches a file iff:
1. pattern can be expanded into the file's filename,
2. the file is inside a directory matched by the option, or
3. the file is a directory which contains a file matched by the
option.
For example,
--exclude /usr/local
matches /usr/local, /usr/local/lib, and /usr/local/lib/netscape. It is
the same as --exclude /usr/local --exclude '/usr/local/**'.
--include /usr/local
specifies that /usr, /usr/local, /usr/local/lib, and
/usr/local/lib/netscape (but not /usr/doc) all be backed up. Thus you
don't have to worry about including parent directories to make sure
that included subdirectories have somewhere to go. Finally,
--include ignorecase:'/usr/[a-z0-9]foo/*/**.py'
1. Globbing patterns like *, **, ?, and [...] are not expanded.
2. Include patterns do not match files in a directory that is
included. So /usr/local in an include file will not match
/usr/local/doc.
3. Lines starting with "+ " are interpreted as include directives,
even if found in a filelist referenced by --exclude-filelist.
Similarly, lines starting with "- " exclude files even if they
are found within an include filelist.
For example, if the file "list.txt" contains the lines:
/usr/local
- /usr/local/doc
/usr/local/bin
+ /var
- /var
then "--include-filelist list.txt" would include /usr, /usr/local, and
/usr/local/bin. It would exclude /usr/local/doc,
/usr/local/doc/python, etc. It neither excludes nor includes
/usr/local/man, leaving the fate of this directory to the next specifi-
cation condition. Finally, it is undefined what happens with /var. A
single file list should not contain conflicting file specifications.
The --include-globbing-filelist and --exclude-globbing-filelist options
also specify filelists, but each line in the filelist will be inter-
preted as a globbing pattern the way --include and --exclude options
are interpreted (although "+ " and "- " prefixing is still allowed).
For instance, if the file "globbing-list.txt" contains the lines:
dir/foo
+ dir/bar
- **
Then "--include-globbing-filelist globbing-list.txt" would be exactly
the same as specifying "--include dir/foo --include dir/bar --exclude
**" on the command line.
Finally, the --include-regexp and --exclude-regexp allow files to be
included and excluded if their filenames match a python regular expres-
sion. Regular expression syntax is too complicated to explain here,
but is covered in Python's library reference. Unlike the --include and
--exclude options, the regular expression options don't match files
containing or contained in matched files. So for instance
--include '[0-9]{7}(?!foo)'
matches any files whose full pathnames contain 7 consecutive digits
which aren't followed by 'foo'. However, it wouldn't match /home even
if /home/ben/1234567 existed.
serve the original id, but only in cases of user and group own-
ership. For ACLs, omit any entry that has a bad user or group
name.
3. However, the --user-mapping-file and --group-mapping-file
options can override this behavior. If either of these options
is given, the policy descriped in 1 and 2 above will be fol-
lowed, but with the mapped user and group instead of the origi-
nal.
The user and group mapping files both have the same form:
old_name_or_id1:new_name_or_id1
old_name_or_id2:new_name_or_id2
<etc>
Each line should contain a name or id, followed by a colon ":", fol-
lowed by another name or id. If a name or id is not listed, they are
treated in the default way described above.
STATISTICS
Every session rdiff-backup saves various statistics into two files, the
session statistics file at rdiff-backup-data/session_statis-
tics.<time>.data and the directory statistics file at rdiff-backup-
data/directory_statistics.<time>.data. They are both text files and
contain similar information: how many files changed, how many were
deleted, the total size of increment files created, etc. However, the
session statistics file is intended to be very readable and only
describes the session as a whole. The directory statistics file is
more compact (and slightly less readable) but describes every directory
backed up. It also may be compressed to save space.
Statistics related options include --print-statistics and --null-sepa-
rator.
Also, rdiff-backup will save various messages to the log file, which is
rdiff-backup-data/backup.log for backup sessions and rdiff-backup-
data/restore.log for restore sessions. Generally what is written to
this file will coincide with the messages diplayed to stdout or stderr,
although this can be changed with the --terminal-verbosity option.
The log file is not compressed and can become quite large if rdiff-
backup is run with high verbosity.
EXIT STATUS
If rdiff-backup finishes successfully, the exit status will be 0. If
there is an unrecoverable (critical) error, it will be non-zero (usu-
ally 1, but don't depend on this specific value). When setting up
rdiff-backup to run automatically (as from cron(8) or similar) it is
probably a good idea to check the exit code.
AUTHOR
Ben Escoto <ben@emerose.org>
Feel free to ask me questions or send me bug reports, but you may want
to see the web page, mentioned below, first.
SEE ALSO
python(1), rdiff(1), rsync(1), ssh(1). The main rdiff-backup web page
is at http://www.nongnu.org/rdiff-backup/. It has more information,
links to the mailing list and CVS, etc.
Version 1.0.5 November 2006 RDIFF-BACKUP(1)
Man(1) output converted with
man2html