Unison

File Synchronization

Unison is a file-synchronization tool for Unix and Windows. It allows two replicas of a collection of files and directories to be stored on different hosts (or different disks on the same host), modified separately, and then brought up to date by propagating the changes in each replica to the other

Pointers

• http://www.cis.upenn.edu/~bcpierce/unison/docs.html
• User Manual and Reference Guide
• http://www.cis.upenn.edu/~bcpierce/unison/faq.html - Unison FAQ

Tips

• use rsync or some other tool to perform the intial sync if you're dealing with a large filesystem with some files that are changing frequently. otherwise you'll wait for a really long time and then probably see unison abort with the dreaded error message "has been modified during synchronization: transfer aborted"
• see FreeBSDCluster for files to exclude when using unison to keep a FreeBSD jail in sync across multiple machines.

Examples

    /usr/local/bin/unison -batch ssh://spike/export/mirror01 /export/mirror01

common.prf

    # Helps out a lot on Windows
    fastcheck = true

    # place new files at the top of the list
    sortnewfirst = true

    # turn on ssh compression
    rshargs = -C

simple.prf

    include common

    root = /home/user/my-unison-root
    root = ssh://user@some.fileserver.com//home/user/my-unison-root

Ignore

- http://www.cis.upenn.edu/~bcpierce/unison/download/releases/stable/unison-manual.html#ignore

    root = /home/user/my-unison-root
    root = ssh://user@some.fileserver.com//home/user/my-unison-root

    ignore = Name {CVS,*.cmo}
    ignore = Path a/b
    ignore = Path */tmp
    ignore = Regex a/b/.*\.ml