RDUP(1)rdupRDUP(1)NAMErdup - generate a file list suitable for making backups
SYNOPSISrdup [-N timestamp] -[-Pcmd,opt1,...,opt7]... [OPTION]... FILELIST
[DIR/FILE]...
DESCRIPTIONrdup is a utility inspired by rsync and the Plan9 way of doing backups.
rdup itself does not backup anything. It only prints a list of files
that are changed, or all files in case of a null dump. It also handles
files that are removed, allowing for correct incremental backups. All
paths printed are absolute. rdup uses the change time (ctime) to decide
whether a file is altered.
It works as follows, for a full dump
1. Crawl all directories, and print all the names found to standard
output. Also check for ._rdup_. files to restore the original
ownership (see the -u flag).
2. Write a filelist with all the names found when crawling. Use
this list to calculate the correct incremental dump.
And for incremental dumps
1. Read in the filelist that was written when doing a full dump.
2. Touch the time stamp file.
3. Crawl all the directories again.
4. Diff 1. and 2. to get two lists; one of removed items and one of
added/modified items.
5. Write the removed items to standard output
6. Write the modified/new items to standard output.
7. Write a new filelist.
The FILELIST is a internal list rdup writes to, to keep track of which
files are in a backup. If you don't want this (i.e. make a full
backup), use /dev/null here. The file /dev/null is handled specially by
rdup: if detected no new file list is written.
The DIRS/FILES can be specified multiple times. These are the directo‐
ries and files you want to backup. If omitted it defaults to the cur‐
rent directory "." .
If the -N timestamp option is not given, all paths found are printed.
Only when a -N timestamp file is given, times can be compared and an
incremental output can be generated.
rdup prints a filelist to standard output. Subsequent programs in a
pipe line can be used to actually implement to backup scheme. After a
run a new FILELIST is written. No warning is given when FILELIST is an
existing file, it just gets overwritten by rdup. New runs will print
out only those files that have actually changed or are removed since
the last run, thereby making incremental backups possible.
Files are checked for changes by comparing the c-time (change time), if
this time is NEWER than the c-time of timestamp file the pathname is
printed to standard output. When files are removed they are also
printed to standard output, but they are prefixed with a '-'. See FOR‐
MAT below. The default format rdup uses is: "%p%T %b %t %u %U %g %G %l
%s\n%n%C"
Note, that rdup also supports hashing of files, this makes it possible
to check the local hash with the hash of the backed up file.
All errors are written to standard error. If the directory or file
does not exist, they are skipped and a warning is emitted.
The general idea is to be very UNIX like and create a bunch of simple
programs which each do a their specific thing very well. With rdup and
a small shell script (50 lines) one can implement encrypted and com‐
pressed backups.
As rdup doesn't backup anything, the backup policy; what you backup,
how you backup, how often and how you restore; is all left to the
scripts and your imagination. To kick start your imagination see rdup-
tr(1), rdup-up(1) and maybe rdup-backups.
OPTIONS-Pcommand,opt0,...,opt6
Filter all output through command. opt0 through opt6 are given
as options to the command. Multiple -P's can be used, there is
however a maximum of seven options for each command. The options
are separated with commas, there must be no space in between.
Due to the nature of pipes in Unix, this pipeline is recreated
for every file processed. Also see 'Child Processes' below.
-F format
Specify a printf-style format to use. See FORMAT below.
-N timestamp
use the c_time of file timestamp as the timestamp to decide what
to include in the incremental backup list. If timestamp does not
exist a full dump is performed.
-M timestamp
As -N, but look at the m_time of timestamp.
-R Reverse the output of rdup. Tools accepting this ouput must cre‐
ate leading directory as they see them. This option allows a
script -- running as a normal user -- to put files in a direc‐
tory which could have 0600 as its permission.
-E file
The file named 'file' contains a list of Perl-compatible regular
expressions (PCRE), one per line, that rdup will use to exclude
names. A '#' at the start of the line can be used to signal a
comment. Empty lines are ignored.
If a directory is excluded, rdup won't descend in that direc‐
tory, so all files in that directory are also excluded.
The directories leading up to the directory to be backed up can
not be excluded. If you use a command line like:
rdup /dev/null /home/miekg/bin
The directories '/home', '/home/miekg', '/home/miekg/bin' are
always printed.
If you want to exclude the file '/home/miekg/blaat' you need to
add the following regular expression: '/home/miekg/blaat'.
If you want to exclude all .mozilla/cache directories of all
users you can use '/home/.*/.mozilla/cache/.*'. This doesn't
exclude the directory itself and I'm assuming that the users'
home directories are found under '/home'.
Also note that rdup does not print directories with a trailing
slash.
-a Restore the original access times on files and directories.
-n Don't honor .nobackup files. Normally if such a file is found
the directory and all files containing it, are not printed to
standard output. Now they are.
-u Output files with a ._rdup_. prefix just as normal files. When
this option is not given these files are skipped by rdup.
-r Only print removed files; entries that start with a `-'. This
option unsets -m.
-m Only print modified/new files; entries that start with a `+'.
This option unsets -r.
-v Be more verbose. When used each path will also be printed to
standard error.
-s size
Don't output files larger than size bytes. This can be used to
limit the amount of data to be transferred when doing a remote
backup. This option only applies to files.
-x Stay on the local filesystem.
-V Print rdup's version.
-h Give an overview of the options.
Child Processes (-P flag)
When creating output you might also want to 'pipe' the contents of each
file through a number of commands, say a compression and encryption
utility. Note that this is different than compressing the entire ar‐
chive as GNU tar allows by using the -z option. So this is where rdup
comes in. It allows you to create a normal archive in which each file
is encrypted (or compressed. reversed or whatever). rdup does this by
forking child processes which transform the content.
If one of the forked children returns an exit code other than zero (0),
it is assumed the whole conversion process failed. In that case rdup
terminates.
As said rdup works by forking off a number of child processes (those
commands named with the -Poption(s)), interconnecting these with
pipes. The current file is connected to the first child. The output
created by these child processes is captured by the parent (rdup). The
contents is then written to standard output in an archive format. As a
picture says more than a thousand words here is an ASCII image of the
process:
+--- ... (stdout) ... ----> archive
/
rdup <--- ... ... <----+
|
loop #files |
|
file ---> cmd1 | cmd2 | ...| cmdN
BACKUPS
With:
rm -f timestamp && rdup-N timestamp LIST DIR
A full-dump filelist is printed to standard output. And with:
rdup-N timestamp LIST DIR
An incremental dump filelist is printed. The file timestamp is used to
save the exact time of rdup's run. The file LIST is used to calculate
the correct incremental dump list, this is needed for files that are
removed, or have a different type.
NON-ROOT BACKUPS
If backups are made by a non-root user or on a filesystem that does not
implement/allow chown (think sshfs mounted by an ordinary user), rdup
creates a seperate file which stores the correct user and group infor‐
mation. If the file's name is foobar a new file called ._rdup_.foobar
is created in the same directory. This file contains one line, for
instance:
root:0/root:0
That tells that the actual ownership should be root:root. For directo‐
ries a ._rdup_. file is created inside the current directory.
FORMAT
The default format rdup uses is: "%p%T %b %t %u %U %g %G %l %s\n%n%C"
The following escape sequences are understood by rdup:
'p': '+' if file is new/modified, '-' if removed
'b': permission bits from lstat(2), octal in four digits
'm': the file mode bits, st_mode from lstat(2), decimal digits
'u': uid
'U': username
'g': gid
'G': groupname
'l': path name length
's': original file size, but see CAVEATS
'n': path name
'N': path name, but in case of a soft- or hardlink only the
link name.
't': time of modification (seconds from epoch)
'H': the SHA1 hash of the regular file, all zeros ("0") for all
other types
'T': file type
- normal file, l symlink, h hardlink, d directory,
c character device, b block device, p named pipe
and s socket.
'C': the content of the file (none for all other types)
To delimit the output of rdup with NULLs you can use '\0' in the format
string.
Any file content is written in a block/chunk based manner. The last
block is signaled with a null block. A block start entry is ASCII and
is formatted as follows: VVBLOCKBBBBB\n . Where 'VV' is the version,
currently at '01', then the literal string 'BLOCK' and then the amount
of bytes (BBBBB), typical '08192'. And then a newline. This look like
this:
01BLOCK08192
<START OF THE FIRST 8192 BYTES>01BLOCK00015
<ANOTHER 15 BYTES>01BLOCK00000
A byte count of zero signals a stop block.
FILELISTrdup writes the (internal) FILELIST in the following format:
MODE DEV INODE LINK UID GID PATH_SIZE FILE_SIZE PATH
Where MODE is the st_mode from stat(2), DEV is the dev id as returned
by the stat call and INODE is the inode number - rdup needs this info
to decide if a directory is renamed. LINK is equal to 'h' for
hardlinks, 'l' for symlinks and otherwise it is '*'. UID and GID are
the numeric user and group id of the file. PATH_SIZE is the length of
PATH. FILE_SIZE the file size. And finally PATH is the path of the
file.
A typical example is:
16893 2050 32085 * 1000 1000 30 4096
/home/miekg/git/rdup/.git/logs
OUTPUT FORMAT
The output generated by rdup is formatted like:
+|-TYPE BITS MTIME UID USER GID GROUP PATH_SIZE FILE_SIZE\n
PATH FILE_CONTENTS
This makes it possible possible for a remote shell script to receive
the actual file contetns and make a backup.
For directories: the FILE_SIZE is zero and no content is printed. Thus:
+d 0755 1260243445 1000 miekg 1000 miekg 11 0\n
/home/miekg
For regular files the following is a sample output:
+- 0644 1260243445 1000 miekg 1000 miekg 32 6\n
/home/miekg/svn/rdup/trunk/aaa/a01BLOCK00006\n
hello\n
01BLOCK00000\n
Where aaa/a is a regular file containing the word 'hello\n'
CAVEATS
Soft- and hardlinks are handled differently when using %n, if you don't
like this behavior use %N. The PATH name is generated from the link's
name and its target. A symlink like
/home/bin/blaat -> /home/bin/bliep
is printed as '/home/bin/blaat -> /home/bin/bliep'. The PATH_SIZE is
modified accordingly, where ' -> ' (4 characters) is also counted. The
FILE_SIZE is not needed for soft- or hardlinks, so it is set the length
of the link's name -- the part left of the ' ->', in this case the
length of '/home/bin/blaat'.
If rdup encounters a hardlink it is handled in the same way, but the
output type is set to 'h' instead of 'l'. A hardlink is only detected
if rdup finds a file with the same inode and device number as a previ‐
ous one, i.e. such hardlinks must be contained in your backup.
Again note: with '%N' only the link's name is printed. The FILE_SIZE is
still set to the length of the link's name.
Device Files
For devices the size field (%s) is changed to hold the major,minor num‐
ber of the device. So if a major number is 8 and the minor number is 0
(under Linux this is /dev/sda), its size will be 8,0. The numbers are
only separated with a comma `,'.
Symlinks
You will probably think rdup will descend into the directory the sym‐
bolic link points to. This is not what actually happens, rdup will
print any directories leading up to the symlink and will not descend
into the directory. GNU tar works the same.
EXIT CODErdup return a zero exit code on success, otherwise 1 is returned. rdup
will abort if a file can not be concatenated, if a regular expression
can not be compiled or if a signal is received.
EXAMPLES
The next set of examples will all make a full dump -- because of the
use of /dev/null. See rdup-tr(1) for more advanced examples.
rdup (mirroring)
Backup:
rdup /dev/null ~/bin | rdup-up -t /shared/backup
Restore:
rdup /dev/null /shared/backup | rdup-up -t /tmp/restore
or
cp -rap /shared/backup /tmp/restore
rdup (archiving)
Backup:
rdup /dev/null ~/bin > my-archive.rdup
Restore:
rdup-up -t /tmp/restore < my-archive.rdup
cpio
Backup:
rdup-R -F '%N\n' /dev/null ~/bin | cpio -o-Hcrc > my-ar‐
chive.cpio
Restore:
cpio -i -d -Hcrc < my-archive.cpio
tar
Backup:
rdup-F '%N\n' /dev/null ~/bin | tar c -f my-archive.tar -T -
--no-recursion
Restore:
tar x -f my-archive.tar
AUTHOR
Written by Miek Gieben.
REPORTING BUGS
Report bugs to <miek@miek.nl>.
SEE ALSO
http:/www.miek.nl/projects/rdup is the main site of rdup. Also see
rdup-tr(1), rdup-up(1) and rdup-backups(7).
COPYRIGHT
Copyright (C) 2005-2011 Miek Gieben. This is free software. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR‐
POSE.
Licensed under the GPL version 3. See the file LICENSE in the source
distribution of rdup.
1.1.14 24 Dec 2005 RDUP(1)
