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 for
more information.
Exactly one command has to be specified on the command line. On the other hand multiple options are allowed.
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
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.
$(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.
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Syrep was written by Lennart Poettering <@PACKAGE_BUGREPORT@>.
Syrep is available at
You are encouraged to improve this documentation, feel free to send me patches. This is free software, after all.