Provided by: yarsync_0.2.1-3_all 
NAME
yarsync - a file synchronization and backup tool
SYNOPSIS
yarsync [-h] [--config-dir DIR] [--root-dir DIR] [-q | -v] command [args]
DESCRIPTION
Yet Another Rsync stores rsync configuration and synchronizes repositories with the
interface similar to git. It is efficient (files in the repository can be removed and
renamed freely without additional transfers), distributed (several replicas of the
repository can diverge, and in that case a manual merge is supported), safe (it takes care
to prevent data loss and corruption) and simple (see this manual).
QUICK START
To create a new repository, enter the directory with its files and type
yarsync init
This operation is safe and will not affect existing files (including configuration files
in an existing repository). Alternatively, run init inside an empty directory and add
files afterward. To complete the initialization, make a commit:
yarsync commit -m "Initial commit"
commit creates a snapshot of the working directory, which is all files in the repository
except yarsync configuration and data. This snapshot is very small, because it uses hard
links. To check how much your directory size has changed, run du(1).
Commit name is the number of seconds since the Epoch (integer Unix time). This allows
commits to be ordered in time, even for hosts in different zones. Though this works on
most Unix systems and Windows, the epoch is platform dependent.
After creating a commit, files can be renamed, deleted or added. To see what was changed
since the last commit, use status. To see the history of existing commits, use log.
Hard links are excellent at tracking file moves or renames and storing accidentally
removed files. Their downside is that if a file gets corrupt, this will apply to all of
its copies in local commits. The 3-2-1 backup rule requires to have at least 3 copies of
data, so let us add a remote repository "my_remote":
yarsync remote add my_remote remote:/path/on/my/remote
For local copies we still call the repositories "remote", but their paths would be local:
yarsync remote add my_drive /mnt/my_drive/my_repo
This command only updated our configuration, but did not make any changes at the remote
path (which may not exist). To make a copy of our repository, run
yarsync clone new-replica-name host:/mnt/my_drive/my_repo
clone copies all repository data (except configuration files) to a new replica with the
given name and adds the new repository to remotes.
To check that we set up the repositories correctly, make a dry run with '-n':
yarsync push -n new-replica-name
If there were no errors and no file transfers, then we have a functioning remote. We can
continue working locally, adding and removing files and making commits. When we want to
synchronize repositories, we push the changes to or pull them from a remote (first with a
--dry-run). This is the recommended workflow, and if we work on different repositories in
sequence and always synchronize changes, our life will be easy. Sometimes, however, we
may forget to synchronize two replicas and they will end up in a diverged state; we may
actually change some files or find them corrupt. Solutions to these problems involve user
decisions and are described in pull and push options.
OPTION SUMMARY
--help, -h show help message and exit
--config-dir=DIR path to the configuration directory
--root-dir=DIR path to the root of the working directory
--quiet, -q decrease verbosity
--verbose, -v increase verbosity
--version, -V print version
COMMAND SUMMARY
checkout restore the working directory to a commit
clone clone a repository
commit commit the working directory
diff print the difference between two commits
init initialize a repository
log print commit logs
pull get data from a source
push send data to a destination
remote manage remote repositories
show print log messages and actual changes for commit(s)
status print updates since last commit
OPTIONS
--help, -h
Prints help message and exits. Default if no arguments are given. After a command
name, prints help for that command.
--config-dir=DIR
Provides the path to the configuration directory if it is detached. Both --config-
dir and --root-dir support tilde expansion for user’s home directory. See SPECIAL
REPOSITORIES for usage details.
--root-dir=DIR
Provides the path to the root of the working directory for a detached repository.
Requires --config-dir. If not set explicitly, the default working directory is the
current one.
--quiet, -q
Decreases verbosity. Does not affect error messages (redirect them if needed).
--verbose, -v
Increases verbosity. May print more rsync commands and output. Conflicts with
--quiet.
--version, -V
Prints the yarsync version and exits. If --help is given, it takes precedence over
--version.
COMMANDS
All commands support the --help option. Commands that can change a repository also
support the --dry-run option.
--dry-run, -n
Prints what will be transferred during a real run, but does not make any changes.
--help, -h
Prints help for a command or a subcommand.
checkout
yarsync checkout [-h] [-n] commit
Restores the working directory to its state during commit. WARNING: this will overwrite
the working directory. Make sure that all important data is committed. Make a dry run
first with -n.
If not the most recent commit was checked out, the repository HEAD (in git terminology,
see git-checkout(1)) becomes detached, which prevents such operations as pull or push. To
advance the repository to its correct state, check out the last commit or make a new one.
commit The commit name (as printed in log or during commit).
clone
yarsync clone [-h] name path|parent-path
One can clone from within an existing repository to parent-path or clone from a repository
at path. In both cases a new directory with the repository is created, having the same
name as the original repository folder. If that directory already exists, clone will fail
(several safety checks are being made). The local repository (origin or clone) will add
another one as a remote.
Note that only data (working directory, commits, logs and synchronization information, not
configuration files) will be cloned. This command will refuse to clone from a repository
with a filter (see SPECIAL REPOSITORIES).
parent-path is useful when we want to clone several repositories into one directory. It
allows us to use the same command for each of them (manually or with mr(1)). If one needs
to have a different directory name for a repository, they can rename it manually (we don’t
require, but strongly encourage having same directory names for all replicas).
Positional arguments
name Name of the new repository.
path Path to the source repository (local or remote). Trailing slash is ignored.
parent-path
Path to the parent directory of the cloned repository (local or remote). Trailing
slash is ignored.
commit
yarsync commit [-h] [-m message] [–limit number]
Commits the working directory (makes its snapshot). See QUICK START for more details on
commits.
--limit=number
Maximum number of commits. If the current number of commits exceeds that, older
ones are removed during commit. See SPECIAL REPOSITORIES for more details.
message
Commit message (used in logs). Can be empty.
diff
yarsync diff [-h] commit [commit]
Prints the difference between two commits (from old to the new one, the order of arguments
is unimportant). If the second commit is omitted, compares commit to the most recent one.
See status for the output format.
commit Commit name.
init
yarsync init [-h] [reponame]
Initializes a yarsync repository in the current directory. Creates a configuration folder
with repository files. Existing configuration and files in the working directory stay
unchanged. Create a first commit for the repository to become fully operational.
reponame
Name of the repository. If not provided on the command line, it will be prompted.
log
yarsync log [-h] [-n number] [-r]
Prints commit logs (from newest to oldest), as well as synchronization information when it
is available. To see changes in the working directory, use status.
Options
--max-count=number, -n
Maximum number of logs shown.
--reverse, -r
Reverse log order.
Example
To print information about the three most recent commits, use
yarsync log -n 3
pull
yarsync pull [-h] [-f | --new | -b | --backup-dir DIR] [-n] source
Gets data from a remote source. The difference between pull and push is mostly only the
direction of transfer.
pull and push bring two repositories into the same state. They synchronize the working
directory, that is they add to the destination new files from source, remove those missing
on source and do all renames and moves of previously committed files efficiently. This is
done in one run, and these changes apply also to logs, commits and synchronization. In
most cases, we do not want our existing logs and commits to be removed though. By
default, several checks are made to prevent data loss:
- local has no uncommitted changes,
- local has not a detached HEAD,
- local is not in a merging state,
- destination has no commits missing on source.
If any of these cases is in effect, no modifications will be made. Note that the remote
may have uncommitted changes itself: always make a dry run with -n first!
To commit local changes to the repository, use commit. HEAD commit could be changed
during checkout (see its section for the solutions). If the destination has commits
missing on source, there are two options: to --force changes to the destination (removing
these commits) or to merge changes inside the local repository with pull --new.
If we pull new commits from the remote, this will bring repository into a merging state.
Merge will be done automatically if the last remote commit is among local ones (in that
case only some older commits were transferred from there). If some recent remote commits
are not present locally, however, this means that histories of the repositories diverged,
and we will need to merge them manually. After we have all local and remote commits and
the union of the working directories in our local repository, we can safely choose the
easiest way for us to merge them. To see the changes, use status and log. For example,
if we added a file in a remote_commit before and it was added now, we can just commit the
changes. If we have made many local changes, renames and removals since then, we may
better checkout our latest commit (remember that all files from the working directory are
present in commits, so it is always safe) and link the new file to the working directory:
ln .ys/commits/<remote_commit>/path/to/file .
(it can be moved to its subdirectory without the risk of breaking hard links). If the
remote commit was actually large, and local changes were recent but small, then we shall
check out the remote commit and apply local changes by hand. After our working directory
is in the desired state, we commit changes and the merge is finished. The result shall be
pushed to the remote without problems.
pull options
--new Do not remove local data that is missing on source. While this option can return
deleted or moved files back to the working directory, it also adds remote logs and
commits that were missing here (for example, old or unsynchronized commits). A
forced push to the remote could remove these logs and commits, and this option
allows one to first pull them to the local repository.
After pull --new the local repository can enter a merging state. See pull
description for more details.
--backup, -b
Changed files in the working directory are renamed (appended with '~'). See
--backup-dir for more details.
--backup-dir DIR
Changed local files are put into a directory DIR preserving their relative paths.
DIR can be an absolute path or relative to the root of the repository. In contrast
to --backup, --backup-dir does not change resulting file names.
This option is convenient for large file trees, because it recreates the existing
file structure of the repository (one doesn’t have to search for new backup files
in all subdirectories). For current rsync version, the command
yarsync pull --backup-dir BACKUP <remote>
will copy updated files from the remote and put them into the directory
"BACKUP/BACKUP" (this is how rsync works). To reduce confusion, make standard pull
first (so that during the backup there are only file updates).
This option is available only for pull, because it is assumed that the user will
apply local file changes after backup. For example, suppose that after a pull
--backup one gets files a and a~ in the working directory. One should first see,
which version is correct. If it is the local file a~, then the backup can be
removed:
mv a~ a
By local we mean the one hard linked with local commits (run ls -i to be sure). If
the remote version is correct though, you need first to overwrite the local version
not breaking the hard links. This can be done with an rsync option "--inplace":
rsync --inplace a a~
mv a~ a
# check file contents and the links
ls -i a .ys/commits/*/a
For a --backup-dir and for longer paths these commands will be longer. Finally, if
you need several versions, just save one of the files under a different name in the
repository.
After you have fixed all corrupt files, push them back to the remote.
pull and push options
--force, -f
Updates the working directory, removing commits and logs missing on source. This
command brings two repositories to the nearest possible states: their working
directories, commits and logs become the same. While working directories are
always identical after pull or push (except for some of the pull options), yarsync
generally refuses to remove existing commits or logs - unless this option is given.
Use it if the destination has really unneeded commits or just remove them manually
(see FILES for details on the commit directory). See also pull --new on how to
fetch missing commits.
push
yarsync push [-h] [-f] [-n] destination
Sends data to a remote destination. See pull for more details and common options.
remote
yarsync remote [-h] [-v] [command]
Manages remote repositories configuration. By default, prints existing remotes. For more
options, see .ys/config.ini in the FILES section.
-v Verbose. Prints remote paths as well.
add
yarsync remote add [-h] repository path
Adds a new remote. repository is the name of the remote in local yarsync configuration
(as it will be used later during pull or push). path has a standard form
[user@]host:[path] for an actually remote host or it can be a local path. Since yarsync
commands can be called from any subdirectory, local path should be absolute. Tilde for
user’s home directory '~' in paths is allowed.
rm
yarsync remote rm [-h] repository
Removes an existing repository from local configuration.
show
Prints remote repositories. Default.
show
yarsync show [-h] commit [commit ...]
Prints log messages and actual changes for commit(s). Changes are shown compared to the
commit before commit. For the output format, see status. Information for several commits
can be requested as well.
commit Commit name.
status
yarsync status [-h]
Prints working directory updates since the last commit and the repository status. If
there were no errors, this command always returns success (irrespective of uncommitted
changes).
Output format of the updates
The output for the updates is a list of changes, including attribute changes, and is based
on the format of rsync --itemize-changes. For example, a line
.d..t...... programming/
means that the modification time 't' of the directory 'd' programming/ in the root of the
repository has changed (files were added or removed from that). All its other attributes
are unchanged ('.').
The output is an 11-letter string of the format "YXcstpoguax", where 'Y' is the update
type, 'X' is the file type, and the other letters represent attributes that are printed if
they were changed. For a newly created file these would be '+', like
>f+++++++++ /path/to/file
The attribute letters are: checksum, size, modification time, permissions, owner and
group. u can be in fact use (access) or creation time, or both. a stands for ACL, and x
for extended attributes. Complete details on the output format can be found in the
rsync(1) manual.
SPECIAL REPOSITORIES
A detached repository is one with the yarsync configuration directory outside the working
directory. To use such repository, one must provide yarsync options --config-dir and
--root-dir with every command (alias(1p) may be of help). To create a detached
repository, use init with these options or move the existing configuration directory
manually. For example, if one wants to have several versions of static Web pages, they
may create a detached repository and publish the working directory without the Web server
having access to the configuration. Alternatively, if one really wants to have both a
continuous synchronization and yarsync backups, they can move its configuration outside,
if that will work. Commits in such repositories can be created or checked out, but pull
or push are currently not supported (one will have to synchronize them manually). A
detached repository is similar to a bare repository in git, but usually has a working
directory.
A repository with a filter can exclude (disable tracking) some files or directories from
the working directory. This may be convenient, but makes synchronization less reliable,
and such repository can not be used as a remote. See rsync-filter in the FILES section
for more details.
A repository can have a commit limit. The maximum number of commits can be set during
commit. pull and push do not check for missing commits on the destination when we are in
a repository with commit limit. It makes a repository with commit limit more like a
central repository. If we have reached the maximum number of commits, older ones are
deleted during a new commit. Commit limit is stored in .ys/COMMIT_LIMIT.txt. It can be
changed or removed at any time. Commit limit was introduced in yarsync v0.2 and was
designed to help against the problem of too many hard links (if it exists).
FILES
All yarsync repository configuration and data is stored in the hidden directory .ys under
the root of the working directory. If the user no longer wants to use yarsync and the
working directory is in the desired state, they can safely remove the .ys directory.
Apart from the working directory, only commits, logs and synchronization data are
synchronized between the repositories. Each repository has its own configuration and
name.
User configuration files
.ys/config.ini
Contains names and paths of remote repositories. This file can be edited directly
or with remote commands according to user’s preference.
yarsync supports synchronization only with existing remotes. A simple
configuration for a remote "my_remote" could be:
[my_remote]
path = remote:/path/on/my/remote
Several sections can be added for more remotes. An example (non-effective)
configuration is created during init. Note that comments in config.ini can be
erased during remote {add,rm}.
Since removable media or remote hosts can change their paths or IP addresses, one
may use variable substitution in paths:
[my_drive]
path = $MY_DRIVE/my_repo
For the substitutions to take the effect, export these variables before run:
$ export MY_DRIVE=/run/media/my_drive
$ yarsync push -n my_drive
If we made a mistake in the variable or path, it will be shown in the printed
command. Always use --dry-run first to ensure proper synchronization.
Another yarsync remote configuration option is host. If both path and host are
present, the effective path will be their concatenation "<host>:<path>". Empty
host means local host and does not prepend the path.
It is possible to set default host for each section from the section name. For
that, add a default section with an option host_from_section_name:
[DEFAULT]
host_from_section_name
Empty lines and lines starting with '#' are ignored. Section names are case-
sensitive. White spaces in a section name will be considered parts of its name.
Spaces around '=' are allowed. Full syntax specification can be found at
<https://docs.python.org/3/library/configparser.html>.
.ys/repo_<name>.txt
Contains the repository name, which is used in logs and usually should coincide
with the remote name (how local repository is called on remotes). The name can be
set during init or edited manually.
Each repository replica must have a unique name. For example, if one has
repositories "programming/" and "music/" on a laptop "my_host", their names would
probably be "my_host", and the names of their copies on an external drive could be
"my_drive" (this is different from git, which uses only the author’s name in logs).
Note that clone from inside a repository for technical reasons creates a temporary
file with the new repository name (which is also written in CLONE_TO_<name>.txt).
If these files due to some errors remain on the system, they can be safely removed.
.ys/rsync-filter
Contains rsync filter rules, which effectively define what data belongs to the
repository. The rsync-filter does not exist by default, but can be added for
flexibility.
For example, the author has a repository "~/work", but wants to keep his
presentations in "tex/" in a separate repository. Instead of having a different
directory "~/work_tex", he adds such rules to rsync-filter:
# all are in git repositories
- /repos
# take care to sync separately
- /tex
In this way, "~/work/tex" and contained git repositories will be excluded from
"~/work" synchronization. Lines starting with '#' are ignored, as well as empty
lines. To complicate things, one could include a subdirectory of "tex" into "work"
with an include filter '+'. For complete details, see FILTER RULES section of
rsync(1).
While convenient for everyday use, filters make backup more difficult. To
synchronize a repository with them, one has to remember that it has subdirectories
that need to be synchronized too. If the remote repository had its own filters,
that would make synchronization even more unreliable. Therefore filters are
generally discouraged: pull and push ignore remote filters (make sure you
synchronize only from a repository with filters), while clone refuses to copy from
a repository with rsync-filter.
yarsync technical directories
.ys/commits/
Contains local commits (snapshots of the working directory). If some of the old
commits are no longer needed (there are too many of them or they contain a large
file), they can be removed. Make sure, however, that all remote repositories
contain at least some of the present commits, otherwise future synchronization will
get complicated. Alternatively, remove unneeded files or folders manually: commits
can be edited, with care taken to synchronize them correctly.
.ys/logs/
Contains text logs produced during commit. They are not necessary, so removing any
of them will not break the repository. If one wants to fix or improve a commit
message though, they may edit the corresponding log (the change will be propagated
during push). It is recommended to store logs even for old deleted commits, which
may be present on formerly used devices.
.ys/sync/
Contains synchronization information for all known reposotories. This information
is transferred between replicas during pull, push and clone, and it allows yarsync
repositories to better support the 3-2-1 backup rule. The information is contained
in empty files with names of the format commit_repo.txt. Pulling (or cloning) from
a repository does not affect its files and does not update its synchronization
information. push (and corresponding clone) updates synchronization for both
replicas. For each repository only the most recent commit is stored. sync
directory was introduced in yarsync v0.2. See the release notes on how to convert
old repositories to the new format or do it manually, if necessary.
If a replica has been permanently removed, its synchronization data must be removed
manually and propagated with --force.
EXIT STATUS
0 Success
1 Invalid option
7 Configuration error
8 Command error
9 System error
2-6,10-14,20-25,30,35
rsync error
If the command could be run successfully, a zero code is returned. Invalid option code is
returned for mistakes in command line argument syntax. Configuration error can occur when
we are outside an existing repository or a yarsync configuration file is missing. If the
repository is correct, but the command is not allowed in its current state (for example,
one can not push or pull when there are uncommitted changes or add a remote with an
already present name), the command error is returned. It is also possible that a general
system error, such as a keyboard interrupt, is raised in the Python interpreter. See
rsync(1) for rsync errors.
DIAGNOSTICS
To check that your clocks (used for properly ordering commits) at different hosts are
synchronized well enough, run
python -c 'import time; print(time.time())'
To make sure that the local repository supports hard links instead of creating file
copies, test it with
du -sh .
du -sh .ys
(can be run during pull or clone if they take too long). The results must be almost the
same. If not, you may not use yarsync on this file system, have large deleted files
stored in old commits or you may have subdirectories excluded with a filter (see SPECIAL
REPOSITORIES section).
To test that a particular file "a" was hard linked to its committed versions, run
ls -i a .ys/commits/*/a
If all is correct, their inodes must be the same.
Hard links can be broken in a cloned git repository (as it could happen with yarsync tests
before), because git does not preserve them. To fix hard links for the whole repository,
run hardlink(1) in its root.
SEE ALSO
rsync(1)
The yarsync page is <https://github.com/ynikitenko/yarsync>.
BUGS
Requires a filesystem with hard links, rsync version at least 3.1.0 (released 28 September
2013) and Python >= 3.6.
Always do a --dry-run before actual changes. Occasionally Python errors are raised
instead of correct return codes. Please report any bugs or make feature requests to
<https://github.com/ynikitenko/yarsync/issues>.
COPYRIGHT
Copyright © 2021-2023 Yaroslav Nikitenko. License GPLv3: GNU GPL version 3
<https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY,
to the extent permitted by law.
AUTHORS
Written by Yaroslav Nikitenko.