Ubuntu Manpage: digup - Digest file updating program.

NAME

       digup - Digest file updating program.

SYNOPSIS

       digup [OPTIONS]

DESCRIPTION

digup is a tool to update md5sum or shasum digest files. It will read existing digest
files, check the current directory for new, updated, modified, renamed or deleted files
and query the user with a summary of changes. After reviewing the updates, they can be
written back to the digest file.

One of the envisioned applications of digup is to update and verify incremental archives
like chronological data storages or music collections. By using digup possibly undesired
changes or lost files can easily be detected while quickly adding new files.

Another purpose could be to automatically verify the integrity of hard disk copies of
archives, as backups to hard disks are becoming increasingly popular. Using a full file
digest scan even slowly creeping bad blocks on old hard disks can be detected. By using a
crontab entry, this check can be performed unattended and routinely.

In normal operation only touched files with newer modification times are fully read and
their digest compared. Optionally a full scan can be performed to test all file contents
against their expected digests.

Symbolic links are supported by either following the link and reading the target's digest
or by saving only the link target path and verifying it against the old one.

The digest files written by digup are compatible with those generated and read by md5sum
and similar programs from the coreutils package. Additional information like file size and
modification time or symlink targets are stored on comment lines.

Four digest algorithms are supported: MD5, SHA1, SHA256 and SHA512. The digest file itself
is also checksummed using CRC32 against unintentional changes. A fast red-black binary
tree is used for the internal file list, allowing fast operation on a large number of
files.

OPTIONS

-b, --batch
Enable non-interactive batch processing mode as needed when run unattended e.g.
from cron. This option also decreases verbosity by one level (--quiet). The
returned error code is set to 1 if any changed, renamed, moved, deleted files or
read errors occur.

-c, --check
Perform a full digest scan of all file contents, thus ignoring file modification
times. Without this option files with equal size and modification time are skipped.

-d, --directory=<path>
Change into this directory before looking for digest files or performing a
recursive scan.

--exclude-marker=<file>
Sets a marker file, often called ".nobackup" in other programs. If this marker file
is found in a directory, the directory itself and all sub-directories are excluded
from the digest scan.

This option is persistent. It is saved in the digest file and will be applied to
all future scans performed to check or update digests.

-f, --file=<file>
Check this file for existing digests and write updates to it. Depending on the
selected digest --type the following file names are used by default: "md5sum.txt",
"sha1sum.txt", "sha256sum.txt" or "sha512sum.txt".

-l, --links
When this flag is enabled, symbolic links (if supported on the platform) are
followed. Otherwise, by default, only the symbolic link's target path is saved and
verified.

-m, --modified
Print only modified, changed, copied, renamed or deleted files. Unchanged files
lines are suppressed. If the whole digest file is clean, then no summary output is
printed at all. This option is useful for crontabs in combination with --batch.

--modify-window=<integer>
Consider modification time deltas of up to this value to be unchanged (the default
is zero). This option is very useful for checking backups on FAT filesystems, as
FAT stores modification times with a precision of only 2 seconds.

-q, --quiet
Reduces the level of verbosity by one.

-r, --restrict=<substring>
Restricts the digest check to filepaths containing the given substring pattern,
other files are skipped. Does NOT imply -c / --check; specify it additionally to
run a full digest check of specific files.

-t, --type=<digest-type>
Select the digest type for newly created digest files. This is not needed for
updating existing one, as the type can inferred from the digest length.

digest-type must be md5, sha1, sha256 or sha512. The default digest type is sha1.

-u, --update
Automatically update the digest file in batch mode. Requires --batch, which is not
automatically activated by this option.

-v, --verbose
Increase the level of verbosity by one.

At level 0 only read errors are printed.

At level 1 the status of each processed file is printed.

And at level 2 (the default) additionally a progress indicator is printed while
reading each file (one dot per megabyte).

-V, --version
Print digup version and exit.

-w, --windows
Ignores modification time deltas of just 1 second (equivalent to --modify-
window=1). Useful for checking backups on FAT filesystems.

EXAMPLES

       To update or create a SHA1 digest file in current directory just run plain
              digup

       Alternatively update or create a SHA512 digest file in /mnt/disk1
              digup -t sha512 -d /mnt/disk1/archive

       A common call for a crontab line is
              digup -bmd /mnt/disk1/archive

       To run a full scan every midnight add a line similar to the following to your crontab
              0 * * * *       digup -bcmd /mnt/disk1/archive

AUTHORS