A command and utility functions for making listings of file content hashcodes and manipulating directory trees based on such a hash index.

This largely exists to solve my "what has changed remotely?" or "what has been filed where?" problems by comparing file trees using the files' content hashcodes.

This does require reading every file once to compute its hashcode, but the hashcodes (and file sizes and mtimes when read) are stored beside the file in .fstags files (see the cs.fstags module), so that a file does not need to be reread on subsequent comparisons.

hashindex knows how to invoke itself remotely using ssh (this does require hashindex to be installed on the remote host) and can thus be used to compare a local and remote tree, for example:

hashindex comm -1 localtree remotehost:remotetree

When you point hashindex at a remote tree, it uses ssh to run hashindex on the remote host, so all the content hashing is done locally to the remote host instead of copying files over the network.

You can also use it to rearrange a tree based on the locations of corresponding files in another tree. Consider a media tree replicated between 2 hosts. If the source tree gets rearranged, the destination can be equivalently rearranged without copying the files, for example:

hashindex rearrange sourcehost:sourcetree localtree

If fstags mv was used to do the original rearrangement then the hashcodes will be copied to the new locations, saving a rescan of the source file. I keep a shell alias mv="fstags mv" so this is routine for me.

A common "backup to remote" use case of mine is addressed by:

hashindex rsync src dst

which rearranges dst based on src, then uses rsync(1) to update dst.

I have a backup script histbackup which works by making a hard link tree of the previous backup and rsyncing into it. It has long been subject to huge transfers if the source tree gets rearranged. Now it has a --hashindex option to get it to run a hashindex rearrange between the hard linking to the new backup tree and the rsync from the source to the new tree.

If network bandwith is limited or quotaed, you can use the comparison function to prepare a list of files missing from the remote location and copy them to a transfer drive for carrying to the remote site when opportune. Example:

hashindex comm -1 -o '{fspath}' src rhost:dst \
| rsync -a --files-from=- src/ xferdir/

I've got a script pref-xfer which does this with some conveniences and sanity checks.

Short summary:

• dir_filepaths: Generator yielding the filesystem paths of the files in dirpath.

• dir_remap: Generator yielding (srcpath,[remapped_paths]) 2-tuples based on the hashcodes keying fspaths_by_hashcode.

• file_checksum: Return the hashcode for the contents of the file at fspath. Warn and return None on OSError.

• hashindex: Generator yielding (hashcode,filepath) 2-tuples for the files in src, which may be a file or a RemotePath or a (host,fspath) 2-tuple or a filesystem path. Note that this yields (None,filepath) for files which cannot be accessed.

• hashindex_map: Construct a mapping of hashcodes to filesystem paths by walking dirpath.

• HashIndexCommand: A tool to generate and use indices of file content hashcodes.

• localpath: Return a filesystem path modified so that it connot be misinterpreted as a remote path such as user@host:path.

• main: Commandline implementation.

• merge: Merge srcpath to dstpath, preserving dstpath if present. Return True if something was done, False if this was a no-op. Raise FileExistsError if dstpath exists with different content.

• paths_remap: Generator yielding (srcpath,fspaths) 2-tuples.

• read_hashindex: A generator which reads line from the file f and yields (hashcode,fspath) 2-tuples for each line. If there are parse errors the hashcode or fspath may be None.

• read_remote_hashindex: A generator which reads a hashindex of a remote directory, This runs: hashindex ls -h hashname -r rdirpath on the remote host. It yields (hashcode,fspath) 2-tuples.

• rearrange: Rearrange the files in dirpath according to the hashcode->[relpaths] fspaths_by_hashcode.

• remote_rearrange: Rearrange a remote directory srcdir on rhost into dstdir on rhost according to the hashcode mapping fspaths_by_hashcode.

• run_remote_hashindex: Run a remote hashindex command. Return the CompletedProcess result or None if doit is false. Note that as with cs.psutils.run, the arguments are resolved via cs.psutils.prep_argv.

Functions

dir_filepaths(*a, fstags: Optional[cs.fstags.FSTags] = <function uses_fstags..

Generator yielding the filesystem paths of the files in dirpath.

dir_remap(srcdirpath: str, fspaths_by_hashcode: Mapping[cs.hashutils.BaseHashCode, List[str]], *, hashname: str)

Generator yielding (srcpath,[remapped_paths]) 2-tuples based on the hashcodes keying fspaths_by_hashcode.

file_checksum(*a, fstags: Optional[cs.fstags.FSTags] = <function uses_fstags..

Return the hashcode for the contents of the file at fspath. Warn and return None on OSError.

hashindex(src: Union[io.TextIOBase, cs.fs.RemotePath, str, Tuple[Optional[str], str]], *, hashname: str, relative: bool = False, runstate: Optional[cs.resources.RunState] = <function uses_runstate..

Generator yielding (hashcode,filepath) 2-tuples for the files in src, which may be a file or a RemotePath or a (host,fspath) 2-tuple or a filesystem path. Note that this yields (None,filepath) for files which cannot be accessed.

hashindex_map(dirpath: str, *, hashname: str, relative=False) -> dict[cs.hashutils.BaseHashCode, list[str]]

Construct a mapping of hashcodes to filesystem paths by walking dirpath.

localpath(fspath: str) -> str

Return a filesystem path modified so that it connot be misinterpreted as a remote path such as user@host:path.

If fspath contains no colon (:) or is an absolute path or starts with ./ then it is returned unchanged. Otherwise a leading ./ is prepended.

main(argv=None)

Commandline implementation.

merge(*a, fstags: Optional[cs.fstags.FSTags] = <function uses_fstags..

Merge srcpath to dstpath, preserving dstpath if present. Return True if something was done, False if this was a no-op. Raise FileExistsError if dstpath exists with different content.

This is aimed at situations such as merging downloads with an existing corpus, which might have hard links etc, so dstpath is the important half of the pair.

NB: symlink_mode is currently disabled.

If 'dstpath' exists, checksum their contents and raise FileExistsError if they differ. If dstpath does not exist, move/link/symlink srcpath to dstpath. This also merges the fstags from srcpath to dstpath.

Otherwise the files have the same content, merge while preserving dstpath.

paths_remap(srcpaths: Iterable[str], fspaths_by_hashcode: Mapping[cs.hashutils.BaseHashCode, List[str]], *, hashname: str)

Generator yielding (srcpath,fspaths) 2-tuples.

read_hashindex(f, start=1, *, hashname: str) -> Iterable[Tuple[Optional[cs.hashutils.BaseHashCode], Optional[str]]]

A generator which reads line from the file f and yields (hashcode,fspath) 2-tuples for each line. If there are parse errors the hashcode or fspath may be None.

read_remote_hashindex(rhost: str, rdirpath: str, *, hashname: str, quiet=True, ssh_exe: str, hashindex_exe: str, relative: bool = False) -> Iterable[Tuple[Optional[cs.hashutils.BaseHashCode], Optional[str]]]

A generator which reads a hashindex of a remote directory, This runs: hashindex ls -h hashname -r rdirpath on the remote host. It yields (hashcode,fspath) 2-tuples.

Parameters:

• rhost: the remote host, or user@host
• rdirpath: the remote directory path
• hashname: the file content hash algorithm name
• ssh_exe: optional ssh command
• hashindex_exe: the remote hashindex executable
• relative: optional flag, default False; if true pass '-r' to the remote hashindex ls command
• check: whether to check that the remote command has a 0 return code, default True

rearrange(srcdirpath: str, rfspaths_by_hashcode, dstdirpath: str | None = None, *, hashname: str, move_mode: bool = False, once: bool = False, symlink_mode=False, do0=False, doit: bool, fstags: cs.fstags.FSTags, runstate: Optional[cs.resources.RunState] = <function uses_runstate..

Rearrange the files in dirpath according to the hashcode->[relpaths] fspaths_by_hashcode.

Parameters:

• srcdirpath: the directory whose files are to be rearranged
• rfspaths_by_hashcode: a mapping of hashcode to relative pathname to which the original file is to be moved
• dstdirpath: optional target directory for the rearranged files; defaults to srcdirpath, rearranging the files in place
• hashname: the file content hash algorithm name
• move_mode: move files instead of linking them
• symlink_mode: symlink files instead of linking them
• do0: rearrange files even of they are empty
• doit: if true do the link/move/symlink, otherwise just print

remote_rearrange(rhost: str, srcdir: str, dstdir: str, fspaths_by_hashcode: Mapping[cs.hashutils.BaseHashCode, List[str]], *, doit: bool, hashindex_exe: str, hashname: str, move_mode: bool, once: bool, quiet: bool, symlink_mode: bool)

Rearrange a remote directory srcdir on rhost into dstdir on rhost according to the hashcode mapping fspaths_by_hashcode.

run_remote_hashindex(rhost: str, argv, *, hashindex_exe: str, **subp_options)

Run a remote hashindex command. Return the CompletedProcess result or None if doit is false. Note that as with cs.psutils.run, the arguments are resolved via cs.psutils.prep_argv.

Parameters:

• rhost: the remote host, or user@host
• argv: the command line arguments to be passed to the remote hashindex command
• check: whether to check that the remote command has a 0 return code, default True Other keyword parameters are passed therough to cs.psutils.run.

Classes

class HashIndexCommand(cs.cmdutils.BaseCommand)

A tool to generate and use indices of file content hashcodes.

Usage summary:

Usage: hashindex [common-options...] subcommand [options...]
  A tool to generate and use indices of file content hashcodes.
  Subcommands:
    comm [common-options...] {-1|-2|-3|-r} {path1|-} {path2|-}
      Compare the filepaths in path1 and path2 by content.
      Options:
        -1  List hashes and paths only present in path1.
        -2  List hashes and paths only present in path2.
        -3  List hashes and paths present in path1 and path2.
        -r  Emit relative paths in the listing.
    help [common-options...] [-l] [-s] [subcommand-names...]
      Print help for subcommands.
      This outputs the full help for the named subcommands,
      or the short help for all subcommands if no names are specified.
      Options:
        -l  Long listing.
        -r  Recurse into subcommands.
        -s  Short listing.
    info [common-options...] [field-names...]
      Recite general information.
      Explicit field names may be provided to override the default listing.
    ls [common-options...] [options...] [[host:]path...]
      Walk filesystem paths and emit a listing.
      The default path is the current directory.
      In quiet mode (-q) the hash indicies are just updated
      and nothing is printed.
      Options:
        -r  Emit relative paths in the listing.
            This requires each command line path to be a directory.
    rearrange [common-options...] [--refdir {[[user@]host:]refdir|-}] [[user@]rhost:]srcdir [dstdir]
      Rearrange files from srcdir into dstdir based on their positions in refdir.
      Arguments:
        refdir    The reference directory, which may be local or remote
                  or "-" indicating that a hash index will be read from
                  standard input.
        srcdir    The directory containing the files to be rearranged,
                  which may be local or remote.
        dstdir    Optional destination directory for the rearranged files.
                  Default is the srcdir.
      Examples:
        rearrange [common-options...] backupdir
          Rearrange the contents of backupdir based on the current directory.
        rearrange [common-options...] --refdir ~/media remote:media
          Rearrange the remote media directory based on the local media directory.
        rearrange [common-options...] remote:dldir remote:storedir
          Rearrange the files in a remote download directory
          into a remote storage directory based on the locations
          in the local current directory.
      Options:
        -1               Rearrange only one file.
        --ln             Hard link files instead of moving them.
        --refdir refdir  Reference directory, default the current directory.
        -s               Symlink mode.
    repl [common-options...]
      Run a REPL (Read Evaluate Print Loop), an interactive Python prompt.
      Options:
        --banner banner  Banner.
    rsync [common-options...] [options] srcdir dstdir [rsync-options...]
      Rearrange dstdir according to srcdir then rsync srcdir into dstdir.
      Options:
        --bwlimit bwlimit  Rsync bandwidth limit, passed to rsync.
        --delete           Delete from dstdir, passed to rsync.
        --partial          Keep partially transferred files, passed to rsync.
    shell [common-options...]
      Run a command prompt via cmd.Cmd using this command's subcommands.

HashIndexCommand.Options(cmd: Optional[str] = None, dry_run: bool = False, force: bool = False, verbosity: int = 0, runstate: Optional[cs.resources.RunState] = None, runstate_signals: Tuple[int] = (<Signals.SIGHUP: 1>, <Signals.SIGINT: 2>, <Signals.SIGQUIT: 3>, <Signals.SIGTERM: 15>), ssh_exe: str = <factory>, hashname: str = 'blake3', move_mode: bool = False, hashindex_exe: str = 'hashindex', symlink_mode: bool = False, relative: Optional[bool] = None, output_format: str = '{hashcode} {fspath}') -> None

Options for HashIndexCommand.

HashIndexCommand.SUBCOMMAND_ARGV_DEFAULT

'ls'

HashIndexCommand.USAGE_FORMAT

('Usage: {cmd} subcommand [options...]\n'
 '  A tool to generate and use indices of file content hashcodes.')

HashIndexCommand.USAGE_KEYWORDS

{'HASHNAME_DEFAULT': 'blake3', 'OUTPUT_FORMAT_DEFAULT': '{hashcode} {fspath}'}

HashIndexCommand.cmd_comm(self, argv, *, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x10c331440>)

Usage: {cmd} {{-1|-2|-3|-r}} {{path1|-}} {{path2|-}} Compare the filepaths in path1 and path2 by content. Options: -1 List hashes and paths only present in path1. -2 List hashes and paths only present in path2. -3 List hashes and paths present in path1 and path2. -r Emit relative paths in the listing.

HashIndexCommand.cmd_ls(self, argv, *, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x10c331940>)

Usage: {cmd} [options...] [[host:]path...] Walk filesystem paths and emit a listing. The default path is the current directory. In quiet mode (-q) the hash indicies are just updated and nothing is printed. Options: -r Emit relative paths in the listing. This requires each command line path to be a directory.

HashIndexCommand.cmd_rearrange(self, argv)

Usage: {cmd} [--refdir {{[[user@]host:]refdir|-}}] [[user@]rhost:]srcdir [dstdir] Rearrange files from srcdir into dstdir based on their positions in refdir. Arguments: refdir The reference directory, which may be local or remote or "-" indicating that a hash index will be read from standard input. srcdir The directory containing the files to be rearranged, which may be local or remote. dstdir Optional destination directory for the rearranged files. Default is the srcdir. Examples: {cmd} backupdir Rearrange the contents of backupdir based on the current directory. {cmd} --refdir ~/media remote:media Rearrange the remote media directory based on the local media directory. {cmd} remote:dldir remote:storedir Rearrange the files in a remote download directory into a remote storage directory based on the locations in the local current directory. Options: -1 Rearrange only one file. --ln Hard link files instead of moving them. --refdir refdir Reference directory, default the current directory. -s Symlink mode.

HashIndexCommand.cmd_rsync(*a, fstags: Optional[cs.fstags.FSTags] = <function uses_fstags.<locals>.<lambda> at 0x10c331800>, **kw)

Usage: {cmd} [options] srcdir dstdir [rsync-options...] Rearrange dstdir according to srcdir then rsync srcdir into dstdir. Options: --bwlimit bwlimit Rsync bandwidth limit, passed to rsync. --delete Delete from dstdir, passed to rsync. --partial Keep partially transferred files, passed to rsync.

HashIndexCommand.poppathspec(argv: List[str], name: str = 'dirspec', check_isdir=False) -> cs.fs.RemotePath

Pop a leading dirspec from argv, a filesystem path with an optional leading [user@]rhost: prefix. Return a (host,fspath) 2-tuple being the remote host (None if omitted) and the filesystem path. Raises GetoptError on a missing or invalid argument.

HashIndexCommand.run_context(*a, fstags: Optional[cs.fstags.FSTags] = <function uses_fstags.<locals>.<lambda> at 0x10c330e00>, **kw)

Sanity check the hashname, open the fstags.