RDUP

Section: rdup (1) Updated: 24 Dec 2005 Local index Up

NAME

rdup - generate a file list suitable for making backups

SYNOPSIS

rdup [-N timestamp] [OPTION]... FILELIST [DIR/FILE]...

DESCRIPTION

rdup 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.

It works as follows, for a full dump

1.: Crawl all directories, and print all the names found to standard output.
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.: Crawl all the directories again.
3.: Diff 1. and 2. to get two lists; one of removed items and one of added/modified items.
4.: Write the removed items to standard output
5.: Write the modified/new items to standard output.
6.: Write a new filelist.
7.: Touch the time stamp file.

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. This is useful when only doing full backups and you want all files to be printed.

The DIRS/FILES can be specified multiple times. These are the directories and files you want to backup. If omitted it defaults to the current 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. If FILELIST is empty or non existent all files in DIR are dumped. This is the same as a null dump. 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 FORMAT below. The default format rdup uses is: "%p%T %b %m %u %g %l %s %n\n"

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 compressed backups.

BACKUP POLICY

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.

OPTIONS

-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. rdup will create/touch timestamp after it has printed the file list. This means if something goes wrong, you still have the original timestamp.

-M timestamp

As -N, but look at the m_time of timestamp.

-R

Reverse the output of rdup. Tools accepting this ouput must create leading directory as they see them. This option allows a script -- running as a normal user -- to put files in a directory 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 discarded. The -0 option also affects the format of this file.

If a directory is excluded, rdup won't descend in that directory, 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.

-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.

-c

Print the files' contents to standard output. This sets the FORMAT string to: "%p%T %b %u %g %l %s\n%n%C"

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, now '01', then the literal string 'BLOCK' and then the amount of bytes, typical '08192'. And then a newline.

An example:

    01BLOCK08192
    <START OF THE FIRST 8192 BYTES>01BLOCK00015
    <ANOTHER 15 BYTES>01BLOCK00000

This option is used when streaming your backup to a remote machine.

-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 once, processed .nobackup files will be printed to standard error. When used twice each path will also be printed to standard error. This is usefull in case of a remote backup (-c) where the normal output is not seen. Using tee(1) might even be better...

-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.

-0

Delimit filelist with NULL's instead of a newline. Use '\0' in the format string to change rdup's output.

-x

Stay on the local filesystem.

-V

Print rdup's version.

-h

Give an overview of the options.

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.

FORMAT

The default format rdup uses is: "%p%T %b %u %g %l %s %n\n"

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
        'g': gid
        'l': path name length
        's': file size, zero if directory, major,minor for devices and see CAVEATS for soft- and hardlinks.
        '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.

FILELIST

rdup writes the FILELIST in the following format:

MODE DEV INODE LINk UID GID PATH_SIZE FILE_SIZE PATH

33204 2050 31970 * 1000 1000 42 887
/home/miekg/git/rdup/.git/hooks/commit-msg

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, other wise 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 default output generated by rdup is formatted like:

: +|-TYPE BITS UID GID PATH_SIZE FILE_SIZE PATH

Where:

o +|-: plus or minus, indicating whether PATH should added or removed.
o TYPE: the type of the file, see %T in FORMAT.
o BITS: the permission of the file, this is a subset of the st_mode from lstat(2). These are four octal digits.
o UID: the numerical user id of PATH. Note that if the first character of the line is '-' (i.e. remove) the UID will be zero.
o GID: the numerical group id of PATH. Note that if the first character of the line is '-' (i.e. remove) the GID will be zero.
o PATH_SIZE: the size of PATH.
o FILE_SIZE: the size of file pointed to by PATH. Note that if the first character of the line is '-' (i.e. remove) the SIZE will be zero. For directories this size will always be zero. Symbolic and hard links are handled differently, see CAVEATS.
o PATH: the pathname

A typical example might look like this:
+- 0755 1000 1000 8 11288 bin/rdup

This example show that the file should be backed up, has a user and group id of 1000, the length of the path is 8 bytes, the size of the file it 11288 and it has "bin/rdup" as a path.

Directories are always printed by rdup.

OUTPUT FORMAT WITH -c

The output generated by rdup -c is formatted like:

: +|-TYPE BITS UID GID PATH_SIZE FILE_SIZE\n
PATH FILE_CONTENTS

This makes it possible possible for a remote shell script to receive the actual file and make a backup.

All field are identical as described in OUTPUT FORMAT, but there is one extra field and also see CAVEATS. The extra field is the FILE_CONTENTS, which concatenates the entire file to standard output.

The output when using the -c is changed as follows, for directories: the FILE_SIZE is zero and no content is printed. Thus:

: +d 0755 1000 1000 11 0\n
/home/miekg

For regular files the following is a sample output:

: +- 0644 1000 1000 32 6\n
/home/miekg/svn/rdup/trunk/aaa/ahello

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 previous 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.

For devices the size field (%s) is changed to hold the major,minor number 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 `,'.

EXIT CODE

rdup 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.