<s>
Unison	B-Application
is	O
a	O
file	B-Application
synchronization	I-Application
tool	O
for	O
Windows	O
and	O
various	O
Unix-like	O
systems	O
(	O
including	O
macOS	B-Application
and	O
Linux	B-Application
)	O
.	O
</s>
<s>
Syncing	O
replicas	O
directly	O
Unison	B-Application
is	O
independent	O
of	O
third-party	O
providers	O
.	O
</s>
<s>
Features	O
of	O
Unison	B-Application
include	O
to	O
handle	O
file	O
changes	O
on	O
both	O
sides	O
of	O
replication	O
;	O
conflicts	O
(	O
same	O
file	O
changed	O
on	O
both	O
sides	O
)	O
are	O
displayed	O
and	O
can	O
be	O
resolved	O
manually	O
,	O
optionally	O
creating	O
backups	O
of	O
changed	O
files	O
.	O
</s>
<s>
Unison	B-Application
allows	O
synchronization	O
via	O
computer	O
networks	O
(	O
LAN	O
,	O
Internet	O
)	O
by	O
direct	O
connection	O
(	O
socket	O
)	O
or	O
tunneled	O
via	O
ssh	O
.	O
</s>
<s>
By	O
using	O
the	O
rsync	B-Application
algorithm	I-Application
only	O
changed	O
blocks	O
of	O
files	O
have	O
to	O
be	O
transferred	O
,	O
thus	O
saving	O
bandwidth	O
.	O
</s>
<s>
Unison	B-Application
can	O
be	O
called	O
via	O
the	O
command	O
line	O
with	O
parameters	O
or	O
controlled	O
via	O
profile	O
files	O
.	O
</s>
<s>
After	O
startup	O
,	O
Unison	B-Application
checks	O
the	O
file	O
inventory	O
per	O
directory	O
or	O
computer	O
and	O
compares	O
the	O
timestamps	O
of	O
the	O
files	O
.	O
</s>
<s>
Afterwards	O
Unison	B-Application
creates	O
a	O
replication	O
list	O
with	O
suggestions	O
for	O
their	O
synchronization	O
and	O
marks	O
conflicts	O
that	O
cannot	O
be	O
resolved	O
automatically	O
.	O
</s>
<s>
GUI	O
versions	O
of	O
Unison	B-Application
exist	O
for	O
interactive	O
use	O
.	O
</s>
<s>
Under	O
Windows	O
and	O
Linux	B-Application
they	O
are	O
generally	O
based	O
on	O
GTK+	O
.	O
</s>
<s>
Compared	O
to	O
rsync	B-Application
,	O
Unison	B-Application
is	O
fully	O
bi-directional	O
and	O
allows	O
the	O
user	O
to	O
detect	O
and	O
reconcile	O
conflicts	O
when	O
both	O
copies	O
of	O
a	O
file	O
have	O
been	O
changed	O
since	O
the	O
last	O
synchronization	O
.	O
</s>
<s>
Before	O
version	O
2.52	O
,	O
a	O
frequent	O
hassle	O
for	O
users	O
was	O
that	O
both	O
computers	O
needed	O
to	O
run	O
the	O
same	O
version	O
of	O
Unison	B-Application
,	O
compiled	O
with	O
the	O
same	O
version	O
of	O
the	O
OCaml	B-Language
libraries	O
.	O
</s>
<s>
This	O
creates	O
problems	O
,	O
since	O
,	O
e.g.	O
,	O
Debian	O
Linux	B-Application
's	O
APT	O
system	O
will	O
not	O
provide	O
the	O
ability	O
to	O
install	O
an	O
arbitrarily	O
chosen	O
version	O
of	O
the	O
software	O
or	O
one	O
compiled	O
with	O
any	O
desired	O
version	O
of	O
the	O
OCaml	B-Language
libraries	O
,	O
if	O
that	O
is	O
what	O
is	O
required	O
by	O
a	O
second	O
machine	O
running	O
a	O
different	O
operating	O
system	O
or	O
packaging	O
system	O
.	O
</s>
<s>
This	O
was	O
solved	O
in	O
version	O
2.52	O
:	O
both	O
client	O
and	O
server	O
can	O
run	O
different	O
versions	O
of	O
Unison	B-Application
,	O
compiled	O
with	O
different	O
OCaml	B-Language
versions	O
,	O
as	O
long	O
as	O
both	O
sides	O
are	O
running	O
at	O
least	O
version	O
2.52	O
.	O
</s>
<s>
If	O
one	O
end	O
is	O
running	O
version	O
2.48	O
or	O
2.51	O
,	O
the	O
other	O
end	O
may	O
run	O
any	O
version	O
from	O
2.52	O
but	O
the	O
OCaml	B-Language
version	O
must	O
match	O
.	O
</s>
<s>
Unison	B-Application
differs	O
from	O
Syncthing	B-Language
in	O
several	O
ways	O
,	O
the	O
main	O
one	O
being	O
that	O
Syncthing	B-Language
is	O
designed	O
for	O
always-on	O
,	O
automated	O
synchronization	O
,	O
whereas	O
Unison	B-Application
is	O
designed	O
for	O
synchronization	O
that	O
is	O
triggered	O
and	O
monitored	O
by	O
the	O
user	O
.	O
</s>
<s>
Syncthing	B-Language
is	O
peer-to-peer	O
,	O
while	O
Unison	B-Application
is	O
not	O
.	O
</s>
