DOKK / manpages / debian 11 / casync / casync.1.en
CASYNC(1) casync CASYNC(1)

casync - casync Documentation

casync [OPTIONS...] make [ARCHIVE | ARCHIVE_INDEX | BLOB_INDEX] [PATH]
casync [OPTIONS...] extract [ARCHIVE | ARCHIVE_INDEX | BLOB_INDEX] [PATH]
casync [OPTIONS...] list [ARCHIVE | ARCHIVE_INDEX | DIRECTORY]
casync [OPTIONS...] mtree [ARCHIVE | ARCHIVE_INDEX | DIRECTORY]
casync [OPTIONS...] stat [ARCHIVE | ARCHIVE_INDEX | DIRECTORY] [PATH]
casync [OPTIONS...] digest [ARCHIVE | BLOB | ARCHIVE_INDEX | BLOB_INDEX | DIRECTORY]
casync [OPTIONS...] mount [ARCHIVE | ARCHIVE_INDEX] PATH
casync [OPTIONS...] mkdev [BLOB | BLOB_INDEX] [NODE]
casync [OPTIONS...] gc BLOB_INDEX | ARCHIVE_INDEX ...

Content-Addressable Data Synchronization Tool

casync make [ARCHIVE | ARCHIVE_INDEX] [DIRECTORY]
casync make [BLOB_INDEX] FILE | DEVICE

This will create either a .catar archive or an .caidx index for for the given DIRECTORY, or a .caibx index for the given FILE or block DEVICE. The type of output is automatically chosen based on the file extension (this may be overridden with --what=). DIRECTORY is optional, and the current directory will be used if not specified.

When a .caidx or .caibx file is created, a .castr storage directory will be created too, by default located in the same directory, and named default.castr unless configured otherwise (see --store= option).

The metadata included in the archive is controlled by the --with-* and --without-* options.

casync extract [ARCHIVE | ARCHIVE_INDEX] [DIRECTORY]
casync extract BLOB_INDEX FILE | DEVICE

This will extract the contents of a .catar archive or .caidx index into the specified DIRECTORY, or the contents specified by BLOB_INDEX to the specified FILE or block DEVICE. DIRECTORY may be omitted, and the current directory will be used by default.

The metadata replayed from the archive is controlled by the --with-* and --without-* options.

casync list [ARCHIVE | ARCHIVE_INDEX | DIRECTORY]

This will list all the files and directories in the specified .catar archive or .caidx index, or the directory. The argument is optional, and the current directory will be used by default.

The output includes the permission mask and file names:

$ casync list /usr/share/doc/casync
drwxr-xr-x
-rw-r--r-- README.md
-rw-r--r-- TODO



casync mtree [ARCHIVE | ARCHIVE_INDEX | DIRECTORY]

This is similar to list, but includes information about each entry in the key=value format defined by BSD mtree(5):

$ casync mtree /usr/share/doc/casync
. type=dir mode=0755 uid=0 gid=0 time=1500343585.721189650
README.md type=file mode=0644 size=7286 uid=0 gid=0 time=1498175562.000000000 sha256digest=af75eacac1f00abf6adaa7510a2c7fe00a4636daf9ea910d69d96f0a4ae85df4
TODO type=file mode=0644 size=2395 uid=0 gid=0 time=1498175562.000000000 sha256digest=316f11a03c08ec39f0328ab1f7446bd048507d3fbeafffe7c32fad4942244b7d



casync stat [ARCHIVE | ARCHIVE_INDEX | DIRECTORY] [PATH]

This will show detailed information about a file or directory PATH, as found in either ARCHIVE or ARCHIVE_INDEX or underneath DIRECTORY. Both arguments are optional. The first defaults to the current directory, and the second the top-level path (.).

Example output:

$ casync stat .


    File: .


    Mode: drwxrwxr-x
FileAttr: ----------


 FATAttr: ---


  Offset: 0


    Time: 2017-07-17 22:53:30.723304050


    User: zbyszek (1000)


   Group: zbyszek (1000)



casync digest [ARCHIVE | BLOB | ARCHIVE_INDEX | BLOB_INDEX | DIRECTORY]

This will compute and print the checksum of the argument. The argument is optional and defaults to the current directory:

$ casync digest
d1698b0c4c27163284abea5d1e369b92e89dd07cb74378638849800e0406baf7
$ casync digest .
d1698b0c4c27163284abea5d1e369b92e89dd07cb74378638849800e0406baf7



casync mount [ARCHIVE | ARCHIVE_INDEX] PATH

This will mount the specified .catar archive or .caidx index at the specified PATH, using the FUSE protocol.

casync mkdev [BLOB | BLOB_INDEX] [NODE]

This will create a block device NODE with the contents specified by the .caibx BLOB_INDEX or just the file or block device BLOB, using the NBD protocol.

Example:

$ sudo casync -v mkdev README.md
Attached: /dev/nbd0
(in another terminal)
$ sudo head -n1 /dev/nbd0
# casync — Content Addressable Data Synchronizer


When casync mkdev is killed, the device is destroyed.

casync gc ARCHIVE_INDEX | BLOB_INDEX ...

This will remove all chunks that are not used by one of the specified indices (one or more blob and archive indices can be given). If --store is not given, the default store for the first index will be used.

This command can be used to prune unused chunks from a shared chunk store.

General options:

Show terse help output
Show brief version information
Set log level (debug, info, err)
Show terse status information during runtime
Only print what would be removed with gc
The primary chunk store to use
Additional chunk store to look for chunks in
The minimal/average/maximum number of bytes in a chunk
Pick digest algorithm (sha512-256 or sha256)
Pick compression algorithm (zstd, xz or gzip)
Additional file or directory to use as seed
Directory to use as encoder cache
Pick encoder cache directory automatically
Maximum bandwidth in bytes/s for remote communication
Don't exclude files with chattr(1)'s +d nodump flag when creating archive
Exclude submounts when creating archive
Don't respect .caexclude files in the file tree
Don't create reflinks from seeds when extracting
Create hardlinks from seeds when extracting
Don't create sparse files when extracting
Don't delete existing files not listed in archive after extraction
When removing existing files, undo chattr(1)'s +i 'immutable' flag when extracting
Don't implicitly add pre-existing output as seed when extracting
List non-recursively
Don't automatically create mount directory if it is missing
Shift UIDs/GIDs
Restrict UIDs/GIDs to range

Input/output selector:

Operate on archive file
Operate on archive index file
Operate on blob file
Operate on blob index file
Operate on directory
Print a list of allowed values (and terminate the program)

Turn on archive feature sets:

Store most accurate information
Store UNIX baseline information
Store FAT information
Store chattr(1) file attributes
Store FAT file attributes
Store file data that requires privileges to restore
Store file data that can exposed again via 'casync mount'

To turn archive features off, --without=… may be used, such as --without=fat-attrs, --without=privileged, etc. To disable all optional features, --without=all may be used. (The positive form --with=all does not make sense, because some features are conflicting. To enable the maximum set of information, use --with=best.)

Individual archive features:

Store reduced 16bit UID/GID information
Store full 32bit UID/GID information
Store user/group names
Store timestamps in 1s granularity
Store timestamps in 1µs granularity
Store timestamps in 1ns granularity
Store timestamps in 2s granularity
Store per-file read only flag
Store full per-file UNIX permissions
Store symbolic links
Store block and character device nodes
Store named pipe nodes
Store AF_UNIX file system socket nodes
Store FAT "hidden" file flag
Store FAT "system" file flag
Store FAT "archive" file flag
Store "append-only" file flag
Store "disable access time" file flag
Store "enable compression" file flag
Store "disable copy-on-write" file flag
Store "disable dumping" file flag
Store "synchronous" directory flag
Store "immutable" file flag
Store "synchronous" file flag
Store "disable compression" file flag
Store "project quota inheritance" flag
Store btrfs subvolume information
Store btrfs subvolume read-only property
Store extended file attributes
Store file access control lists
Store SElinux file labels
Store file capabilities
Store ext4/XFS quota project ID

(and similar: --without=16bit-uids, --without=32bit-uids, ...)

The various --with= and --without= parameters control the precise set of metadata to store in the archive, or restore when extracting. These flags only apply if casync operates on the file system level.

When generating an archive or index from a file system directory tree, some files and directories are excluded by default and others may optionally be excluded:

1.
Files and directories of virtual API file systems exposed by the kernel (i.e. procfs, sysfs, cgroupfs, devpts … — but not tmpfs/devtmpfs) are excluded unconditionally.
2.
Depending on whether symlinks, device nodes, fifos and sockets are enabled for archiving with --with= and --without=, file nodes of these types are excluded.
3.
By default, files and directories with the +d chattr(1) flag set are excluded, however this behaviour may be turned off with --exclude-nodump=no.
4.
Optionally, files and directories contained in submounts of the specified file system tree are excluded, if --exclude-submounts=yes is specified.
5.
By default, any files and directories listed in .caexclude files in the file hierarchy are excluded, however interpretation of these files may be turned off with --exclude-file=no. These files operate similar to git's .gitignore concept: they are read as text file where each line is either empty/starts with # (in which case they have no effect, which may be used for commenting), or list a globbing path pattern of files/directories to ignore. If a line contains no / character the line applies to the directory the .caexclude file is located in as well as all child directories of it. If it contains at least one / character it is considered stricly relative to the directory the .caexclude file is located in. .caexclude files may appear in any directory of the file system tree that is archived, however they have no effect when placed in directories that are marked for exclusion via .caexclude files placed further up in the directory tree. When a line ends in a / character it applies to directories only, and not regular files or other file node types. If a line is prefixed with a ! character matching files are excluded from the exclusion, i.e. the effect of other matching lines that are not prefixed like this is cancelled for matching files. ! lines unconditionally take precedence over lines not marked like this. Moreover, lines prefixed with ! also cancel the effect of patterns in .caexclude files placed in directories further up the tree.

February 21, 2021 1