syrep(1) A file repository synchronization tool


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 ...


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.


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


-h | --help (command)
Print help and exit
-V | --version (command)
Print version information and exit


--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.


--info (command)
Show information about a repository or snapshot, such as origin, current timestamp and version, database size.


--history (command)
Show the version and timestamp history of a snapshot's updates


--dump (command)
Show a structure dump of a repository or 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.


--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".


--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.


--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


--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


--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


--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).


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.


$(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.


0 Success

Nonzero Failure


Syrep was written by Lennart Poettering <mzflerc (at) 0pointer (dot) de>.

Syrep is available at

You are encouraged to improve this documentation, feel free to send me patches. This is free software, after all.


This man page was written using xml2man(1) by Oliver Kurth.