A file synchronization tool, distributed under GNU GPL, written in OCaml.

Unison is able to synchronize single files and directories over network. It works as a normal program and need not to be run as root, doesn't require any extra daemons, just a copy of the binary in both ends. Further, it's cross-platform, able to communicate with Unix, Windows and Mac systems. It also supports SSH-encrypted connections.

I used Unison to solve my filekeeping problems. Originally, I just needed to copy my Mozilla bookmarks to keep them on sync in home and on university box, and for that, scp was enough; after that, when multiple files were needed, it got tricky. I found Unison better than manual copying of the file anyway: You don't need to say where the file is supposed to go, because Unison can say which file was modified and can copy the file from there. Also, it apparently uses some strange diff format for transportation, because it is vastly faster than scp'ing the whole file.

It has a very clear command-line interface, but also has graphical (GTK+, at least) frontends.

Home page, as of writing: <http://www.cis.upenn.edu/~bcpierce/unison/>. Also available as a Debian package.

UNISON is the largest trade union in the United Kingdom with over 1.3 million members, created in 1993 from the merger of the following unions;

Its members work predomninantly in the public sector, but due to privatisation of various public services has a growing number working in the private sector as well. The Union has organised itself into six service groups, which give an indication of the breadth of its activities;

  • Business and Environment
  • Community and Voluntary Sector
  • Education Services
  • Health Care
  • Local Government
  • Police Services

U"ni*son [LL. unisonus having the same sound; L. unus one + sonus a sound: cf. F. unisson, It. unisono. See One, and Sound a noise.]


Harmony; agreement; concord; union.

2. Mus.

Identity in pitch; coincidence of sounds proceeding from an equality in the number of vibrations made in a given time by two or more sonorous bodies. Parts played or sung in octaves are also said to be in unison, or in octaves.

⇒ If two cords of the same substance have equal length, thickness, and tension, they are said to be in unison, and their sounds will be in unison. Sounds of very different qualities and force may be in unison, as the sound of a bell may be in unison with a sound of a flute. Unison, then, consists in identity of pitch alone, irrespective of quality of sound, or timbre, whether of instruments or of human voices. A piece or passage is said to be sung or played in unison when all the voices or instruments perform the same part, in which sense unison is contradistinguished from harmony.


A single, unvaried.



In unison, in agreement; agreeing in tone; in concord.


© Webster 1913.

U"ni*son ]


Sounding alone.


[sounds] intermixed with voice, Choral or unison. Milton.

2. Mus.

Sounded alike in pitch; unisonant; unisonous; as, unison passages, in which two or more parts unite in coincident sound.


© Webster 1913.

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