Ubuntu Manpage: bup-index - print and/or update the bup filesystem index

NAME

       bup-index - print and/or update the bup filesystem index

SYNOPSIS

       bup  index <-p|-m|-s|-u|--clear|--check> [-H] [-l] [-x] [--fake-valid] [--no-check-device]
       [--fake-invalid] [-f indexfile] [--exclude path] [--exclude-from  filename]  [--exclude-rx
       pattern] [--exclude-rx-from filename] [-v] <paths...>

DESCRIPTION

       bup  index  manipulates the filesystem index, which is a cache of absolute paths and their
       metadata (attributes, SHA-1 hashes, etc.).  The bup index is similar in  function  to  the
       git(1) index, and the default index can be found in $BUP_DIR/bupindex.

       Creating  a  backup  in bup consists of two steps: updating the index with bup index, then
       actually backing up the files (or a subset of the files) with bup  save.   The  separation
       exists for these reasons:

       1. There  is more than one way to generate a list of files that need to be backed up.  For
          example, you might want to use inotify(7) or dnotify(7).

       2. Even if you back up files to multiple destinations (for  added  redundancy),  the  file
          names,  attributes,  and  hashes  will  be  the same each time.  Thus, you can save the
          trouble of repeatedly re-generating the list of files for each backup set.

       3. You may want to use the data tracked by bup index for other purposes (such as  speeding
          up other programs that need the same information).

NOTES

At the moment, bup will ignore Linux attributes (cf. chattr(1) and lsattr(1)) on some
systems (any big-endian systems where sizeof(long) < sizeof(int)). This is because the
Linux kernel and FUSE currently disagree over the type of the attr system call arguments,
and so on big-endian systems there’s no way to get the results without the risk of stack
corruption (http://lwn.net/Articles/575846/). In these situations, bup will print a
warning the first time Linux attrs are relevant during any index/save/restore operation.

bup makes accommodations for the expected “worst-case” filesystem timestamp resolution –
currently one second; examples include VFAT, ext2, ext3, small ext4, etc. Since bup
cannot know the filesystem timestamp resolution, and could be traversing multiple
filesystems during any given run, it always assumes that the resolution may be no better
than one second.

As a practical matter, this means that index updates are a bit imprecise, and so bup save
may occasionally record filesystem changes that you didn’t expect. That’s because, during
an index update, if bup encounters a path whose actual timestamps are more recent than one
second before the update started, bup will set the index timestamps for that path (mtime
and ctime) to exactly one second before the run, – effectively capping those values.

This ensures that no subsequent changes to those paths can result in timestamps that are
identical to those in the index. If that were possible, bup could overlook the
modifications.

You can see the effect of this behavior in this example (assume that less than one second
elapses between the initial file creation and first index run):

$ touch src/1 src/2
# A "sleep 1" here would avoid the unexpected save.
$ bup index src
$ bup save -n src src # Saves 1 and 2.
$ date > src/1
$ bup index src
$ date > src/2 # Not indexed.
$ bup save -n src src # But src/2 is saved anyway.

Strictly speaking, bup should not notice the change to src/2, but it does, due to the
accommodations described above.

MODES

       -u, --update
              recursively update the index for the given paths and  their  descendants.   One  or
              more  paths  must  be  specified, and if a path ends with a symbolic link, the link
              itself will be indexed, not the target.  If no mode option is  given,  --update  is
              the  default,  and paths may be excluded by the --exclude, --exclude-rx, and --one-
              file-system options.

       -p, --print
              print the contents of the index.  If paths are given, shows the given  entries  and
              their  descendants.   If  no  paths  are  given,  shows the entries starting at the
              current working directory (.).

       -m, --modified
              prints only files which are marked as modified (ie.  changed since the most  recent
              backup) in the index.  Implies -p.

       -s, --status
              prepend a status code (A, M, D, or space) before each path.  Implies -p.  The codes
              mean, respectively, that a file is marked in the index as added, modified, deleted,
              or unchanged since the last backup.

       --check
              carefully  check index file integrity before and after updating.  Mostly useful for
              automated tests.

       --clear
              clear the default index.

OPTIONS

-H, --hash
for each file printed, prepend the most recently recorded hash code. The hash code
is normally generated by bup save. For objects which have not yet been backed up,
the hash code will be 0000000000000000000000000000000000000000. Note that the hash
code is printed even if the file is known to be modified or deleted in the index
(ie. the file on the filesystem no longer matches the recorded hash). If this is
a problem for you, use --status.

-l, --long
print more information about each file, in a similar format to the -l option to
ls(1).

-x, --xdev, --one-file-system
don’t cross filesystem boundaries when traversing the filesystem – though as with
tar and rsync, the mount points themselves will still be indexed. Only applicable
if you’re using -u.

--fake-valid
mark specified paths as up-to-date even if they aren’t. This can be useful for
testing, or to avoid unnecessarily backing up files that you know are boring.

--fake-invalid
mark specified paths as not up-to-date, forcing the next “bup save” run to re-check
their contents.

-f, --indexfile=indexfile
use a different index filename instead of $BUP_DIR/bupindex.

--exclude=path
exclude path from the backup (may be repeated).

--exclude-from=filename
read –exclude paths from filename, one path per-line (may be repeated). Ignore
completely empty lines.

--exclude-rx=pattern
exclude any path matching pattern, which must be a Python regular expression
(http://docs.python.org/library/re.html). The pattern will be compared against the
full path, without anchoring, so “x/y” will match “ox/yard” or “box/yards”. To
exclude the contents of /tmp, but not the directory itself, use “^/tmp/.”. (may be
repeated)

Examples:

• `/foo$' - exclude any file named foo

• `/foo/$' - exclude any directory named foo

• `/foo/.' - exclude the content of any directory named foo

• `^/tmp/.' - exclude root-level /tmp’s content, but not /tmp itself

--exclude-rx-from=filename
read –exclude-rx patterns from filename, one pattern per-line (may be repeated).
Ignore completely empty lines.

--no-check-device
don’t mark an entry invalid if the device number (stat(2) st_dev) changes. This
can be useful when indexing remote, automounted, or snapshot filesystems (LVM,
Btrfs, etc.), where the device number isn’t fixed.

-v, --verbose
increase log output during update (can be used more than once). With one -v, print
each directory as it is updated; with two -v, print each file too.

EXAMPLES

              bup index -vux /etc /var /usr

BUP

       Part of the bup(1) suite.

AUTHORS

       Avery Pennarun <apenwarr@gmail.com>.