NAME
syrep - A file repository synchronization tool
SYNOPSIS
syrep [options...] --list SNAPSHOT ...
syrep [options...] --info SNAPSHOT ...
syrep [options...] --history SNAPSHOT ...
syrep [options...] --dump SNAPSHOT ...
syrep [options...] --update DIRECTORY ...
syrep [options...] --diff SNAPSHOT SNAPSHOT
syrep [options...] --merge SNAPSHOT DIRECTORY
syrep [options...] --merge PATCH DIRECTORY
syrep [options...] --merge DIRECTORY DIRECTORY
syrep [options...] --makepatch DIRECTORY SNAPSHOT
syrep [options...] --extract SNAPSHOT ...
syrep [options...] --cleanup DIRECTORY ...
syrep [options...] --forget SNAPSHOT ...
DESCRIPTION
Syrep is a generic file repository synchronization tool. It may be used
to synchronize large file hierarchies bidirectionally by exchanging
patch files. Syrep is truely peer-to-peer, no central servers are
involved. Synchronizations between more than two repositories are
supported. The patch files may be transferred via offline media, e.g.
removable hard disks or compact discs.
Files are tracked by their message digests, currently MD5.
Syrep was written to facilitate the synchronization of two large
digital music repositories without direct network connection. Patch
files of several gigabytes are common in this situation.
Syrep is able to cope with 64 bit file sizes. (LFS)
Syrep is optimized for speed. It may make use of a message digest cache
to accelerate the calculation of digests of a whole directory
hierarchy.
A syrep repository is a normal UNIX directory tree containing a special
directory .syrep with a file current.syrep (called snapshot) which
holds file system history data. A directory is turned into a syrep
repository by running --update on it. Snapshots are used to perform
basic tasks like comparing repositories (command --diff) or creating
patches between them (command --make-patch).
Syrep will ignore all files and directories that have the extended
attribute user.syrep set to omit. Currently, this works on Linux only.
Keep in mind, that only newer kernel versions and some file system
support extended attributes. See attr(5) for more information.
GENERAL OPTIONS
Exactly one command has to be specified on the command line. On the
other hand multiple options are allowed.
-v | --verbose (option)
Enable more verbose operation
-T | --local-temp (option)
Use temporary directory inside repository. This is very useful
when the file repository you apply patches to is on a different
partition than /tmp, because files my be hard linked instead of
copied. This requires a read-writable file system however.
--ignore-origin (option)
Normally syrep warns you if you update, merge or makepatch a
repository with a matching snapshot not generated on the
original host, and asks the user if he really wants to proceed.
This option may be used to disable this question.
-z | --compress (option)
Compress output snapshots or patches. This may slow down syrep
extraordinarily and is more or less useless if the data to
compress is already compressed. I suggest using it for --update
but not for --makepatch if the file repository contains MP3 or
MPEG files only.
-p | --progress (option)
Show a rotating dash while executing operations
GENERAL COMMANDS
-h | --help (command)
Print help and exit
-V | --version (command)
Print version information and exit
LISTING SNAPSHOT CONTENTS
--list (command)
Command for listing the file log of a repository snapshot
--show-deleted (option)
Show deleted entries
--show-by-md (option)
Show files by message digests. This option collides with --sort.
--show-times (option)
Show first and last seen times
--sort (option)
Sort file listing chronologically. This option collides with
--show-by-md.
SHOWING SNAPSHOT INFORMATION
--info (command)
Show information about a repository or snapshot, such as origin,
current timestamp and version, database size.
SHOWING SNAPSHOT HISTORY
--history (command)
Show the version and timestamp history of a snapshot’s updates
DUMPING SNAPSHOT CONTENTS
--dump (command)
Show a structure dump of a repository or snapshot
UPDATING A SNAPSHOT
--update (command)
Update or create a snapshot for a repository directory. That is:
iterate through the specified hierarchy and update the snapshot
log information accordingly.
-SSTRING | --snapshot=STRING (option)
Use the specified snapshot file instead of the one contained in
the repository directory. This may be helpful if your file
hierarchy is read only.
-CSTRING | --cache=STRING (option)
Use the specified message digest cache file instead of the one
contained in the repository directory. This may be helpful if
your file hierarchy is read only or when you plan to maintain a
system wide message digest cache. In the latter case you should
use --no-purge as well.
--no-cache (option)
Don’t use a message digest cache.
--no-purge (option)
Don’t purge obsolete entries from cache after update run. The
may be useful if you plan to maintain a system wide message
digest cache.
--ro-cache (option)
Use cache in a read only fashion
--check-dev (option)
Store information about the device where the file resides when
storing an entry about it in the message digest cache. Since
nowadays device identifiers cannot be longer considered stable,
this options defaults to off.
SHOWING DIFFERENCES BETWEEN TWO SNAPSHOTS
--diff (command)
Show difference between two repositories or snapshots
-s | --sizes (option)
Show the sizes of the files to copy. This works only when acting
on a local repository and for the local files.
-H | --human-readable (option)
Only useful when using with -s. When enabled shows file sizes in
human readable form, i.e. "3.5 MB" instead of "3670016".
MERGING A SNAPSHOT, A PATCH OR A REPOSITORY INTO A REPOSITORY
--merge (command)
Merge a snapshot, a patch or a repository into a repository.
Afterwards, you should run --update on the repository to update
the snapshot.
-q | --question (option)
Ask a question before each action
-P | --prune-empty (option)
Prune empty directories
--keep-trash (option)
Don’t empty trash. Deleted files are copied into a trash folder
inside the repository directory. If this option is specified
this trash is not emptied when the operation is completed.
--check-md (option)
Check message digests of files before deleting or replacing
them. NB: This worsens syrep’s performance and is thus not
enabled by default.
--always-copy (option)
As default syrep tries to hard link files instead of copying
them. With this option syrep will always do a copy, regardless
if a hard link is possible or not. This is especially useful
when doing bi-directory merges. NB: This worsens syrep’s
performance and is thus not enabled by default.
MAKING A PATCH FOR A SNAPSHOT AGAINST A DIRECTORY
--makepatch (command)
Make a patch against the specified repository. The patch is
written to STDOUT unless -o is specified.
-oSTRING | --output-file=STRING (option)
Write output to specified file instead of STDOUT
--include-all (option)
Include files in patch which do exist on the other side under a
different name
EXTRACTING A SNAPSHOT’S CONTENTS
--extract (command)
Extract the contents of a snapshot or patch to the local
directory unless -D is specified.
-DSTRING | --output-directory=STRING (option)
Write output to specified directory
CLEANING UP A REPOSITORY
--cleanup (command)
Remove syrep info from repository
-lINT | --cleanup-level=INT
1: just remove temporary data and trash (default); 2: remove
message digest cache as well; 3: remove all syrep data
FORGETTING OUTDATED SNAPSHOT INFORMATION
--forget (command)
Repackage the snapshot file dropping outdated information. Use
this if your snapshot files get too large.
-R DAYS | --remember=DAYS (option)
Information about how many days in the past should be kept? This
defaults to 180 (half a year).
REPOSITORIES, SNAPSHOTS AND PATCHES
A syrep file repository is a POSIX file hierarchy with some additional
log data, which is used to track changes. Normally this log data is
saved as "snapshot" in the file $(REPOSITORY)/.syrep/current.syrep. You
may create and update it by running --update. The more often this log
is updated the better modifications may be tracked. Therefore this
operation should be called at least once a day via cron(8)
Two snapshots of two distinct repositories (possibly from different
hosts) may be compared with ---diff. This will show you which files
should be copied or deleted from or to the other repository.
--makepatch will attach the data of the local missing in the remote
repository to a snapshot and write it to a patch file. This file should
be transferred to the other repository and applied there with --merge.
Keep in mind that patches contain the snapshot data of the originating
host. Because of that you may use it as a snapshot, e.g. by running
--diff on it. On the other hand you are also able to merge snapshots
without attached patch data to a repository. This will do all required
deletions and renames, but naturally won’t add any new data to the file
tree.
To extract the contents of a patch you may use --extract. This will
write all files contained in the patch or snapshot to the local
directory, including snapshot log data. Files are named by their
message digests.
FILES
$(REPOSITORY)/.syrep/current.syrep is the current snapshot of the
repository. It is created and updated by running --update on the
directory. Use this file to create patches on other repositories
against this one. This file may be compressed by specifiying --compress
when running --update.
$(REPOSITORY)/.syrep/md-cache is the message digest cache which may be
used to accelerate the repeated operation of ---update. It associates
device numbers, inode numbers, file sizes and modification times with
the message digest calculated for that file. The file is only valid on
the host it was created on since it contains device numbers.
$(REPOSITORY)/.syrep/trash/ is the trash directory used by --merge.
Files are moved in here on deletion. After successful completion it is
emptied unless --keep-trash is specified.
$(REPOSITORY)/.syrep/tmp/ is used as temporary file space for
extracting snaphots when option --local-temp is used.
RETURN VALUES
0 Success
Nonzero Failure
AUTHOR
Syrep was written by Lennart Poettering <mzflerc (at) 0pointer (dot)
de>.
Syrep is available at http://0pointer.de/lennart/projects/syrep/
You are encouraged to improve this documentation, feel free to send me
patches. This is free software, after all.
SEE ALSO
rsync(1), cron(8), attr(5)
COMMENTS
This man page was written using xml2man(1) by Oliver Kurth.