Provided by: unison-2.53_2.53.3-2_amd64 
NAME
unison — a multi-platform bi-directional file synchronization tool
SYNOPSIS
unison [options]
unison root1 root2 [options]
unison profilename [options]
DESCRIPTION
Unison is a file-synchronization tool for POSIX-compliant systems (e.g. *BSD and GNU/Linux),
macOS 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.
Unison has been in use for over 20 years and many people use it to synchronize data they
care about.
Unison shares a number of features with other tools. Some of the distinguishing features
are:
• Unlike simple mirroring or backup utilities, Unison can deal with updates to both
replicas of a distributed directory structure.
• Unison works across platforms, allowing you to synchronize a Windows laptop with a Unix
server, for example.
• Unlike most distributed filesystems, Unison is a user-level program that simply uses
normal systems calls: there is no need to modify the kernel, to have superuser
privileges on either host, or to have a FUSE implementation.
• Unison works between any pair of machines connected to the internet, typically
communicating over ssh(1), but also directly over TCP. It is careful with network
bandwidth, and runs well over slow links. Transfers of small updates to large files are
optimized using a compression protocol similar to rsync(1).
• Unison is resilient to failure. It is careful to leave the replicas and its own private
structures in a sensible state at all times, even in case of abnormal termination or
communication failures.
OPTION SUMMARY
Basic options:
General:
-doc xxx show documentation ('-doc topics' lists topics)
-version print version and exit
What to sync:
-group synchronize group attributes
-ignore xxx add a pattern to the ignore list
-ignorenot xxx add a pattern to the ignorenot list
-nocreation xxx prevent file creations on one replica
-nodeletion xxx prevent file deletions on one replica
-noupdate xxx prevent file updates and deletions on one replica
-owner synchronize owner
-path xxx path to synchronize
-perms n part of the permissions which is synchronized
-root xxx root of a replica (should be used exactly twice)
-times synchronize modification times
How to sync:
-batch batch mode: ask no questions at all
How to sync (text interface (CLI) only):
-auto automatically accept default (nonconflicting) actions
-silent print nothing except error messages
-terse suppress status messages
Text interface (CLI):
-i interactive profile mode (text UI); command-line only
Advanced options:
Fine-tune sync:
-acl synchronize ACLs
-atomic xxx add a pattern to the atomic list
-follow xxx add a pattern to the follow list
-force xxx force changes from this replica to the other
-forcepartial xxx add a pattern to the forcepartial list
-ignorecase xxx identify upper/lowercase filenames (true/false/default)
-immutable xxx add a pattern to the immutable list
-immutablenot xxx add a pattern to the immutablenot list
-links xxx allow the synchronization of symbolic links
(true/false/default)
-merge xxx add a pattern to the merge list
-nocreationpartial xxx add a pattern to the nocreationpartial list
-nodeletionpartial xxx add a pattern to the nodeletionpartial list
-noupdatepartial xxx add a pattern to the noupdatepartial list
-prefer xxx choose this replica's version for conflicting changes
-preferpartial xxx add a pattern to the preferpartial list
-rsrc xxx synchronize resource forks (true/false/default)
-xattrignore xxx add a pattern to the xattrignore list
-xattrignorenot xxx add a pattern to the xattrignorenot list
-xattrs synchronize extended attributes (xattrs)
How to sync:
-backup xxx add a pattern to the backup list
-backupcurr xxx add a pattern to the backupcurr list
-backupcurrnot xxx add a pattern to the backupcurrnot list
-backupdir xxx directory for storing centralized backups
-backuploc xxx where backups are stored ('local' or 'central')
-backupnot xxx add a pattern to the backupnot list
-backupprefix xxx prefix for the names of backup files
-backups (deprecated) keep backup copies of all files (see also
'backup')
-backupsuffix xxx a suffix to be added to names of backup files
-confirmbigdel ask about whole-replica (or path) deletes (default true)
-confirmmerge ask for confirmation before committing results of a merge
-copyonconflict keep copies of conflicting files
-dontchmod when set, never use the chmod system call
-fastcheck xxx do fast update detection (true/false/default)
-fat use appropriate options for FAT filesystems
-ignoreinodenumbers ignore inode number changes when detecting updates
-maxbackups n number of backed up versions of a file
-numericids don't map uid/gid values by user/group names
-sortbysize list changed files by size, not name
-sortfirst xxx add a pattern to the sortfirst list
-sortlast xxx add a pattern to the sortlast list
-sortnewfirst list new before changed files
How to sync (text interface (CLI) only):
-repeat xxx synchronize repeatedly (text interface only)
-retry n re-try failed synchronizations N times (text ui only)
Text interface (CLI):
-color xxx use color output for text UI (true/false/default)
-dumbtty do not change terminal settings in text UI
Graphical interface (GUI):
-height n height (in lines) of main window in graphical interface
Remote connections:
-addversionno add version number to name of unison on server
-clientHostName xxx set host name of client
-halfduplex (deprecated) force half-duplex communication with the
server
-killserver kill server when done (even when using sockets)
-listen xxx listen on this name or addr in server socket mode (can
repeat)
-rsync activate the rsync transfer mode (default true)
-servercmd xxx name of unison executable on remote server
-socket xxx act as a server on a socket
-sshargs xxx other arguments (if any) for remote shell command
-sshcmd xxx path to the ssh executable
-stream (deprecated) use a streaming protocol for transferring
file contents (default true)
-testserver exit immediately after the connection to the server
-xferbycopying optimize transfers using local copies (default true)
Archive management:
-ignorearchives ignore existing archive files
Other:
-addprefsto xxx file to add new prefs to
-contactquietly suppress the 'contacting server' message during startup
-copymax n maximum number of simultaneous copyprog transfers
-copyprog xxx external program for copying large files
-copyprogrest xxx variant of copyprog for resuming partial transfers
-copythreshold n use copyprog on files bigger than this (if >=0, in Kb)
-diff xxx set command for showing differences between files
-ignorelocks ignore locks left over from previous run (dangerous!)
-include xxx include a profile's preferences
-key xxx define a keyboard shortcut for this profile (in some UIs)
-label xxx provide a descriptive string label for this profile
-log record actions in logfile (default true)
-logfile xxx logfile name
-maxerrors n maximum number of errors before a directory transfer is
aborted
-maxsizethreshold n prevent transfer of files bigger than this (if >=0, in
Kb)
-maxthreads n maximum number of simultaneous file transfers
-mountpoint xxx abort if this path does not exist
-rootalias xxx register alias for canonical root names
-showarchive show 'true names' (for rootalias) of roots and archive
-source xxx include a file's preferences
-ui xxx select UI ('text' or 'graphic'); command-line only
-unicode xxx assume Unicode encoding in case insensitive mode
-watch when set, use a file watcher process to detect changes
Expert options:
-debug xxx debug module xxx ('all' -> everything, 'verbose' -> more)
-dumparchives dump contents of archives just after loading
-fastercheckUNSAFE skip computing fingerprints for new files (experts only!)
-selftest run internal tests and exit
OPTIONS
Most of the options can be given as command line arguments or in a profile. On command line,
but not in a profile, the options are specified with a leading dash. Like this: -option.
acl When this flag is set to true, the ACLs of files and directories are synchronized.
The type of ACLs depends on the platform and filesystem support. On Unix-like
platforms it can be NFSv4 ACLs, for example.
addprefsto xxx
By default, new preferences added by Unison (e.g., new ignore clauses) will be
appended to whatever preference file Unison was told to load at the beginning of the
run. Setting the preference addprefsto filename makes Unison add new preferences to
the file named filename instead.
addversionno
When this flag is set to true, Unison will use unison-currentmajorversionnumber
instead of just unison as the remote server command (note that the minor version
number is dropped -- e.g., unison-2.51). This allows multiple binaries for different
versions of unison to coexist conveniently on the same server: whichever version is
run on the client, the same version will be selected on the server.
atomic xxx
This preference specifies paths for directories whose contents will be considered as
a group rather than individually when they are both modified. The backups are also
made atomically in this case. The option backupcurr however has no effect on atomic
directories.
auto When set to true, this flag causes the user interface to skip asking for
confirmations on non-conflicting changes. (More precisely, when the user interface
is done setting the propagation direction for one entry and is about to move to the
next, it will skip over all non-conflicting entries and go directly to the next
conflict.)
backup xxx
Including the preference -backup pathspec causes Unison to keep backup files for
each path that matches pathspec; directories (nor their permissions or any other
metadata) are not backed up. These backup files are kept in the directory specified
by the backuplocation preference. The backups are named according to the
backupprefix and backupsuffix preferences. The number of versions that are kept is
determined by the maxbackups preference. The syntax of pathspec is described in
Section “Path Specification” in the manual.
backupcurr xxx
Including the preference -backupcurr pathspec causes Unison to keep a backup of the
current version of every file matching pathspec. This file will be saved as a
backup with version number 000. Such backups can be used as inputs to external
merging programs, for instance. See the documentation for the merge preference. For
more details, see Section “Merging Conflicting Versions” in the manual. The syntax
of pathspec is described in Section “Path Specification” in the manual.
backupcurrnot xxx
Exceptions to backupcurr, like the ignorenot preference.
backupdir xxx
If this preference is set, Unison will use it as the name of the directory used to
store backup files specified by the backup preference, when backuplocation is set to
central. It is checked after the UNISONBACKUPDIR environment variable.
backuploc xxx
This preference determines whether backups should be kept locally, near the original
files, or in a central directory specified by the backupdir preference. If set to
local, backups will be kept in the same directory as the original files, and if set
to central, backupdir will be used instead.
backupnot xxx
The values of this preference specify paths or individual files or regular
expressions that should not be backed up, even if the backup preference selects
them—i.e., it selectively overrides backup.
backupprefix xxx
When a backup for a file NAME is created, it is stored in a directory specified by
backuplocation, in a file called backupprefixNAMEbackupsuffix. backupprefix can
include a directory name (causing Unison to keep all backup files for a given
directory in a subdirectory with this name), and both backupprefix and backupsuffix
can contain the string $VERSION, which will be replaced by the age of the backup (1
for the most recent, 2 for the second most recent, and so on...). This keyword is
ignored if it appears in a directory name in the prefix; if it does not appear
anywhere in the prefix or the suffix, it will be automatically placed at the
beginning of the suffix. One thing to be careful of: If the backuploc preference is
set to local, Unison will automatically ignore all files whose prefix and suffix
match backupprefix and backupsuffix. So be careful to choose values for these
preferences that are sufficiently different from the names of your real files.
backups
(Deprecated) Setting this flag to true is equivalent to setting backuplocation to
local and backup to Name *.
backupsuffix xxx
See backupprefix for full documentation.
batch When this is set to true, the user interface will ask no questions at all.
Non-conflicting changes will be propagated; conflicts will be skipped.
clientHostName xxx
When specified, the host name of the client will not be guessed and the provided
host name will be used to find the archive.
color xxx
When set to true, this flag enables color output in text mode user interface. When
set to false, all color output is disabled. Default is to enable color if the
NO_COLOR environment variable is not set.
confirmbigdel
When this is set to true, Unison will request an extra confirmation if it appears
that the entire replica has been deleted, before propagating the change. If the
batch flag is also set, synchronization will be aborted. When the path preference is
used, the same confirmation will be requested for top-level paths. (At the moment,
this flag only affects the text user interface.) See also the mountpoint preference.
confirmmerge
Setting this preference causes both the text and graphical interfaces to ask the
user if the results of a merge command may be committed to the replica or not. Since
the merge command works on temporary files, the user can then cancel all the effects
of applying the merge if it turns out that the result is not satisfactory. In
batch-mode, this preference has no effect. Default is false.
contactquietly
If this flag is set, Unison will skip displaying the `Contacting server' message
(which some users find annoying) during startup.
copymax n
A number indicating how many instances of the external copying utility Unison is
allowed to run simultaneously (default to 1).
copyonconflict
When this flag is set, Unison will make a copy of files that would otherwise be
overwritten or deleted in case of conflicting changes, and more generally whenever
the default behavior is overridden. This makes it possible to automatically resolve
conflicts in a fairly safe way when synchronizing continuously, in combination with
the -repeat watch and -prefer newer preferences.
copyprog xxx
A string giving the name of an external program that can be used to copy large files
efficiently (plus command-line switches telling it to copy files in-place). The
default setting invokes rsync with appropriate options—most users should not need to
change it.
copyprogrest xxx
A variant of copyprog that names an external program that should be used to continue
the transfer of a large file that has already been partially transferred. Typically,
copyprogrest will just be copyprog with one extra option (e.g., --partial, for
rsync). The default setting invokes rsync with appropriate options—most users should
not need to change it.
copythreshold n
A number indicating above what filesize (in kilobytes) Unison should use the
external copying utility specified by copyprog. Specifying 0 will cause all copies
to use the external program; a negative number will prevent any files from using it.
The default is -1. See Section “Making Unison Faster on Large Files” in the manual
for more information.
debug xxx
This preference is used to make Unison print various sorts of information about what
it is doing internally on the standard error stream. It can be used many times, each
time with the name of a module for which debugging information should be printed.
Possible arguments for debug can be found by looking for calls to Util.debug in the
sources (using, e.g., grep). Setting -debug all causes information from all modules
to be printed (this mode of usage is the first one to try, if you are trying to
understand something that Unison seems to be doing wrong); -debug verbose turns on
some additional debugging output from some modules (e.g., it will show exactly what
bytes are being sent across the network).
diff xxx
This preference can be used to control the name and command-line arguments of the
system utility used to generate displays of file differences. The default is `diff
-u OLDER NEWER'. If the value of this preference contains the substrings CURRENT1
and CURRENT2, these will be replaced by the names of the files to be diffed. If the
value of this preference contains the substrings NEWER and OLDER, these will be
replaced by the names of files to be diffed, NEWER being the most recently modified
file of the two. Without any of these substrings, the two filenames will be appended
to the command. In all cases, the filenames are suitably quoted.
doc xxx
The command-line argument -doc secname causes unison to display section secname of
the manual on the standard output and then exit. Use -doc all to display the whole
manual, which includes exactly the same information as the printed and HTML manuals,
modulo formatting. Use -doc topics to obtain a list of the names of the various
sections that can be printed.
dontchmod
By default, Unison uses the 'chmod' system call to set the permission bits of files
after it has copied them. But in some circumstances (and under some operating
systems), the chmod call always fails. Setting this preference completely prevents
Unison from ever calling chmod.
dumbtty
When set to true, this flag makes the text mode user interface avoid trying to
change any of the terminal settings. (Normally, Unison puts the terminal in `raw
mode', so that it can do things like overwriting the current line.) This is useful,
for example, when Unison runs in a shell inside of Emacs. When dumbtty is set,
commands to the user interface need to be followed by a carriage return before
Unison will execute them. (When it is off, Unison recognizes keystrokes as soon as
they are typed.) This preference has no effect on the graphical user interface.
dumparchives
When this preference is set, Unison will create a file unison.dump on each host,
containing a text summary of the archive, immediately after loading it.
fastcheck xxx
When this preference is set to true, Unison will use the modification time and
length of a file as a `pseudo inode number' when scanning replicas for updates,
instead of reading the full contents of every file. (This does not apply to the very
first run, when Unison will always scan all files regardless of this switch). Under
Windows, this may cause Unison to miss propagating an update if the modification
time and length of the file are both unchanged by the update. However, Unison will
never overwrite such an update with a change from the other replica, since it always
does a safe check for updates just before propagating a change. Thus, it is
reasonable to use this switch under Windows most of the time and occasionally run
Unison once with fastcheck set to false, if you are worried that Unison may have
overlooked an update. For backward compatibility, yes, no, and default can be used
in place of true, false, and auto. See Section “Fast Update Detection” in the
manual for more information.
fastercheckUNSAFE
THIS FEATURE IS STILL EXPERIMENTAL AND SHOULD BE USED WITH EXTREME CAUTION. When
this flag is set to true, Unison will compute a 'pseudo-fingerprint' the first time
it sees a file (either because the file is new or because Unison is running for the
first time). This enormously speeds update detection, but it must be used with care,
as it can cause Unison to miss conflicts: If a given path in the filesystem contains
files on both sides that Unison has not yet seen, and if those files have the same
length but different contents, then Unison will not notice the presence of a
conflict. If, later, one of the files is changed, the changed file will be
propagated, overwriting the other. Moreover, even when the files are initially
identical, setting this flag can lead to potentially confusing behavior: if a newly
created file is later touched without being modified, Unison will treat this
conservatively as a potential change (since it has no record of the earlier
contents) and show it as needing to be propagated to the other replica. Most users
should leave this flag off -- the small time savings of not fingerprinting new files
is not worth the cost in terms of safety. However, it can be very useful for power
users with huge replicas that are known to be already synchronized (e.g., because
one replica is a newly created duplicate of the other, or because they have
previously been synchronized with Unison but Unison's archives need to be rebuilt).
In such situations, it is recommended that this flag be set only for the initial run
of Unison, so that new archives can be created quickly, and then turned off for
normal use.
fat When this is set to true, Unison will use appropriate options to synchronize
efficiently and without error a replica located on a FAT filesystem on a non-Windows
machine: do not synchronize permissions (perms = 0); never use chmod (dontchmod =
true); treat filenames as case insensitive (ignorecase = true); do not attempt to
synchronize symbolic links (links = false); ignore inode number changes when
detecting updates (ignoreinodenumbers = true). Any of these change can be overridden
by explicitly setting the corresponding preference in the profile.
follow xxx
Including the preference -follow pathspec causes Unison to treat symbolic links
matching pathspec as `invisible' and behave as if the object pointed to by the link
had appeared literally at this position in the replica. See Section “Symbolic Links”
in the manual for more details. The syntax of pathspec is described in Section “Path
Specification” in the manual.
force xxx
Including the preference -force root causes Unison to resolve all differences (even
non-conflicting changes) in favor of root. This effectively changes Unison from a
synchronizer into a mirroring utility. You can also specify a unique prefix or
suffix of the path of one of the roots or a unique prefix of the hostname of a
remote root. You can also specify -force newer (or -force older) to force Unison to
choose the file with the later (earlier) modtime. In this case, the -times
preference must also be enabled. This preference is overridden by the forcepartial
preference. This preference should be used only if you are sure you know what you
are doing!
forcepartial xxx
Including the preference forcepartial = PATHSPEC -> root causes Unison to resolve
all differences (even non-conflicting changes) in favor of root for the files in
PATHSPEC (see Section “Path Specification” in the manual for more information). This
effectively changes Unison from a synchronizer into a mirroring utility. You can
also specify a unique prefix or suffix of the path of one of the roots or a unique
prefix of the hostname of a remote root. You can also specify forcepartial PATHSPEC
-> newer (or forcepartial PATHSPEC -> older) to force Unison to choose the file with
the later (earlier) modtime. In this case, the -times preference must also be
enabled. This preference should be used only if you are sure you know what you are
doing!
group When this flag is set to true, the group attributes of the files are synchronized.
Whether the group names or the group identifiers are synchronized depends on the
preference numerids.
halfduplex
(Deprecated) When this flag is set to true, Unison network communication is forced
to be half duplex (the client and the server never simultaneously emit data). If you
experience unstabilities with your network link, this may help.
height n
Used to set the height (in lines) of the main window in the graphical user
interface.
i Provide this preference in the command line arguments to enable interactive profile
manager in the text user interface. Currently only profile listing and interactive
selection are available. Preferences like batch and silent remain applicable to
synchronization functionality.
ignore xxx
Including the preference -ignore pathspec causes Unison to completely ignore paths
that match pathspec (as well as their children). This is useful for avoiding
synchronizing temporary files, object files, etc. The syntax of pathspec is
described in Section “Path Specification” in the manual, and further details on
ignoring paths is found in Section “Ignoring Paths” in the manual.
ignorearchives
When this preference is set, Unison will ignore any existing archive files and
behave as though it were being run for the first time on these replicas. It is not a
good idea to set this option in a profile: it is intended for command-line use.
ignorecase xxx
When set to true, this flag causes Unison to treat filenames as case
insensitive—i.e., files in the two replicas whose names differ in (upper- and
lower-case) `spelling' are treated as the same file. When the flag is set to false,
Unison will treat all filenames as case sensitive. Ordinarily, when the flag is set
to default, filenames are automatically taken to be case-insensitive if either host
is running Windows or OSX. In rare circumstances it may be useful to set the flag
manually.
ignoreinodenumbers
When set to true, this preference makes Unison not take advantage of inode numbers
during fast update detection. This switch should be used with care, as it is less
safe than the standard update detection method, but it can be useful with
filesystems which do not support inode numbers.
ignorelocks
When this preference is set, Unison will ignore any lock files that may have been
left over from a previous run of Unison that was interrupted while reading or
writing archive files; by default, when Unison sees these lock files it will stop
and request manual intervention. This option should be set only if you are positive
that no other instance of Unison might be concurrently accessing the same archive
files (e.g., because there was only one instance of unison running and it has just
crashed or you have just killed it). It is probably not a good idea to set this
option in a profile: it is intended for command-line use.
ignorenot xxx
This preference overrides the preference ignore. It gives a list of patterns (in
the same format as ignore) for paths that should definitely not be ignored, whether
or not they happen to match one of the ignore patterns. Note that the semantics of
ignore and ignorenot is a little counter-intuitive. When detecting updates, Unison
examines paths in depth-first order, starting from the roots of the replicas and
working downwards. Before examining each path, it checks whether it matches ignore
and does not match ignorenot; in this case it skips this path and all its
descendants. This means that, if some parent of a given path matches an ignore
pattern, then it will be skipped even if the path itself matches an
ignorenotpattern. In particular, putting ignore = Path * in your profile and then
using ignorenot to select particular paths to be synchronized will not work.
Instead, you should use the pathpreference to choose particular paths to
synchronize.
immutable xxx
This preference specifies paths for directories whose immediate children are all
immutable files — i.e., once a file has been created, its contents never changes.
When scanning for updates, Unison does not check whether these files have been
modified; this can speed update detection significantly (in particular, for mail
directories).
immutablenot xxx
This preference overrides immutable.
include xxx
Include preferences from a profile. include name reads the profile “name” (or file
“name” in the .unison directory if profile “name” does not exist) and includes its
contents as if it was part of a profile or given directly on command line.
key xxx
Used in a profile to define a numeric key (0-9) that can be used in the user
interface to switch immediately to this profile.
killserver
When set to true, this flag causes Unison to kill the remote server process when the
synchronization is finished. This behavior is the default for ssh connections, so
this preference is not normally needed when running over ssh; it is provided so that
socket-mode servers can be killed off after a single run of Unison, rather than
waiting to accept future connections. (Some users prefer to start a remote socket
server for each run of Unison, rather than leaving one running all the time.)
label xxx
Used in a profile to provide a descriptive string documenting its settings. (This is
useful for users that switch between several profiles, especially using the `fast
switch' feature of the graphical user interface.)
links xxx
When set to true, this flag causes Unison to synchronize symbolic links. When the
flag is set to false, symbolic links will be ignored during update detection.
Ordinarily, when the flag is set to default, symbolic links are synchronized except
when one of the hosts is running Windows. On a Windows client, Unison makes an
attempt to detect if symbolic links are supported and allowed by user privileges.
You may have to get elevated privileges to create symbolic links. When the flag is
set to { default} and symbolic links can't be synchronized then an error is
produced during update detection.
listen xxx
When acting as a server on a TCP socket, Unison will by default listen on "any"
address (0.0.0.0 and [::]). This command-line argument allows to specify a different
listening address and can be repeated to listen on multiple addresses. Listening
address can be specified as a host name or an IP address.
log When this flag is set, Unison will log all changes to the filesystems on a file.
logfile xxx
By default, logging messages will be appended to the file unison.log in your .unison
directory. Set this preference if you prefer another file. It can be a path relative
to your .unison directory. Sending SIGUSR1 will close the logfile; the logfile will
be re-opened (and created, if needed) automatically, to allow for log rotation.
maxbackups n
This preference specifies the number of backup versions that will be kept by unison,
for each path that matches the predicate backup. The default is 2.
maxerrors n
This preference controls after how many errors Unison aborts a directory transfer.
Setting it to a large number allows Unison to transfer most of a directory even when
some files fail to be copied. The default is 1. If the preference is set too high,
Unison may take a long time to abort in case of repeated failures (for instance,
when the disk is full).
maxsizethreshold n
A number indicating above what filesize (in kilobytes) Unison should flag a conflict
instead of transferring the file. This conflict remains even in the presence of
force or prefer options. A negative number will allow every transfer independently
of the size. The default is -1.
maxthreads n
This preference controls how much concurrency is allowed during the transport phase.
Normally, it should be set reasonably high to maximize performance, but when Unison
is used over a low-bandwidth link it may be helpful to set it lower (e.g. to 1) so
that Unison doesn't soak up all the available bandwidth. The default is the special
value 0, which mean 20 threads when file content streaming is deactivated and 1000
threads when it is activated.
merge xxx
This preference can be used to run a merge program which will create a new version
for each of the files and the backup, with the last backup and both replicas. The
syntax of pathspec -> cmd is described in Section “Path Specification” in the
manual, and further details on Merging functions are present in Section “Merging
Conflicting Versions” in the manual.
mountpoint xxx
Including the preference -mountpoint PATH causes Unison to double-check, at the end
of update detection, that PATH exists and abort if it does not. This is useful when
Unison is used to synchronize removable media. This preference can be given more
than once. See Section “Mount Points and Removable Media” in the manual.
nocreation xxx
Including the preference -nocreation root prevents Unison from performing any file
creation on root root. You can also specify a unique prefix or suffix of the path
of one of the roots or a unique prefix of the hostname of a remote root. This
preference can be included twice, once for each root, if you want to prevent any
creation.
nocreationpartial xxx
Including the preference nocreationpartial = PATHSPEC -> root prevents Unison from
performing any file creation in PATHSPEC on root root (see Section “Path
Specification” in the manual for more information). It is recommended to use
BelowPath patterns when selecting a directory and all its contents.
nodeletion xxx
Including the preference -nodeletion root prevents Unison from performing any file
deletion on root root. You can also specify a unique prefix or suffix of the path
of one of the roots or a unique prefix of the hostname of a remote root. This
preference can be included twice, once for each root, if you want to prevent any
deletion.
nodeletionpartial xxx
Including the preference nodeletionpartial = PATHSPEC -> root prevents Unison from
performing any file deletion in PATHSPEC on root root (see Section “Path
Specification” in the manual for more information). It is recommended to use
BelowPath patterns when selecting a directory and all its contents.
noupdate xxx
Including the preference -noupdate root prevents Unison from performing any file
update or deletion on root root. You can also specify a unique prefix or suffix of
the path of one of the roots or a unique prefix of the hostname of a remote root.
This preference can be included twice, once for each root, if you want to prevent
any update.
noupdatepartial xxx
Including the preference noupdatepartial = PATHSPEC -> root prevents Unison from
performing any file update or deletion in PATHSPEC on root root (see Section “Path
Specification” in the manual for more information). It is recommended to use
BelowPath patterns when selecting a directory and all its contents.
numericids
When this flag is set to true, groups and users are synchronized numerically, rather
than by name. The special uid 0 and the special group 0 are never mapped via
user/group names even if this preference is not set.
owner When this flag is set to true, the owner attributes of the files are synchronized.
Whether the owner names or the owner identifiers are synchronizeddepends on the
preference numerids.
path xxx
When no path preference is given, Unison will simply synchronize the two entire
replicas, beginning from the given pair of roots. If one or more path preferences
are given, then Unison will synchronize only these paths and their children. (This
is useful for doing a fast sync of just one directory, for example.) Note that path
preferences are interpreted literally—they are not regular expressions.
perms n
The integer value of this preference is a mask indicating which permission bits
should be synchronized. It is set by default to $0o1777$: all bits but the set-uid
and set-gid bits are synchronised (synchronizing these latter bits can be a security
hazard). If you want to synchronize all bits, you can set the value of this
preference to $-1$. If one of the replica is on a FAT [Windows] filesystem, you
should consider using the fat preference instead of this preference. If you need
Unison not to set permissions at all, set the value of this preference to $0$ and
set the preference dontchmod to true.
prefer xxx
Including the preference -prefer root causes Unison always to resolve conflicts in
favor of root, rather than asking for guidance from the user, except for paths
marked by the preference merge. (The syntax of root is the same as for the root
preference, plus the special values newer and older.) You can also specify a unique
prefix or suffix of the path of one of the roots or a unique prefix of the hostname
of a remote root. This preference is overridden by the preferpartial preference.
This preference should be used only if you are sure you know what you are doing!
preferpartial xxx
Including the preference preferpartial = PATHSPEC -> root causes Unison always to
resolve conflicts in favor of root, rather than asking for guidance from the user,
for the files in PATHSPEC (see Section “Path Specification” in the manual for more
information). (The syntax of root is the same as for the root preference, plus the
special values newer and older.) You can also specify a unique prefix or suffix of
the path of one of the roots or a unique prefix of the hostname of a remote root.
This preference should be used only if you are sure you know what you are doing!
repeat xxx
Setting this preference causes the text-mode interface to synchronize repeatedly,
rather than doing it just once and stopping. If the argument is a number, Unison
will pause for that many seconds before beginning again. When the argument is watch,
Unison relies on an external file monitoring process to synchronize whenever a
change happens. You can combine the two with a + character to use file monitoring
and also do a full scan every specificed number of seconds. For example, watch+3600
will react to changes immediately and additionally do a full scan every hour.
retry n
Setting this preference causes the text-mode interface to try again to synchronize
updated paths where synchronization fails. Each such path will be tried N times.
root xxx
Each use of this preference names the root of one of the replicas for Unison to
synchronize. Exactly two roots are needed, so normal modes of usage are either to
give two values for root in the profile, or to give no values in the profile and
provide two on the command line. Details of the syntax of roots can be found in
Section “Roots” in the manual. The two roots can be given in either order; Unison
will sort them into a canonical order before doing anything else. It also tries to
`canonize' the machine names and paths that appear in the roots, so that, if Unison
is invoked later with a slightly different name for the same root, it will be able
to locate the correct archives.
rootalias xxx
When calculating the name of the archive files for a given pair of roots, Unison
replaces any roots matching the left-hand side of any rootalias rule by the
corresponding right-hand side.
rsrc xxx
When set to true, this flag causes Unison to synchronize resource forks and HFS
meta-data. On filesystems that do not natively support resource forks, this data is
stored in Carbon-compatible ._AppleDouble files. When the flag is set to false,
Unison will not synchronize these data. Ordinarily, the flag is set to default, and
these data are automatically synchronized if either host is running OSX. In rare
circumstances it is useful to set the flag manually.
rsync Unison uses the 'rsync algorithm' for 'diffs-only' transfer of updates to large
files. Setting this flag to false makes Unison use whole-file transfers instead.
Under normal circumstances, there is no reason to do this, but if you are having
trouble with repeated 'rsync failure' errors, setting it to false should permit you
to synchronize the offending files.
selftest
Run internal tests and exit. This option is mostly for developers and must be used
carefully: in particular, it will delete the contents of both roots, so that it can
install its own files for testing. This flag only makes sense on the command line.
When it is provided, no preference file is read: all preferences must be specified
on thecommand line. Also, since the self-test procedure involves overwriting the
roots and backup directory, the names of the roots and of the backupdir preference
must include the string "test" or else the tests will be aborted. (If these are not
given on the command line, dummy subdirectories in the current directory will be
created automatically.)
servercmd xxx
This preference can be used to explicitly set the name of the Unison executable on
the remote server (e.g., giving a full path name), if necessary.
showarchive
When this preference is set, Unison will print out the 'true names'of the roots, in
the same form as is expected by the rootalias preference.
silent When this preference is set to true, the textual user interface will print nothing
at all, except in the case of errors. Setting silent to true automatically sets the
batch preference to true.
socket xxx
Start unison as a server listening on a TCP socket (with TCP port number as
argument) or a local socket (aka Unix domain socket) (with socket path as argument).
sortbysize
When this flag is set, the user interface will list changed files by size (smallest
first) rather than by name. This is useful, for example, for synchronizing over slow
links, since it puts very large files at the end of the list where they will not
prevent smaller files from being transferred quickly. This preference (as well as
the other sorting flags, but not the sorting preferences that require patterns as
arguments) can be set interactively and temporarily using the 'Sort' menu in the
graphical and text user interfaces.
sortfirst xxx
Each argument to sortfirst is a pattern pathspec, which describes a set of paths.
Files matching any of these patterns will be listed first in the user interface. The
syntax of pathspec is described in Section “Path Specification” in the manual.
sortlast xxx
Similar to sortfirst, except that files matching one of these patterns will be
listed at the very end.
sortnewfirst
When this flag is set, the user interface will list newly created files before all
others. This is useful, for example, for checking that newly created files are not
`junk', i.e., ones that should be ignored or deleted rather than synchronized.
source xxx
Include preferences from a file. source name reads the file “name” in the .unison
directory and includes its contents as if it was part of a profile or given directly
on command line.
sshargs xxx
The string value of this preference will be passed as additional arguments (besides
the host name and the name of the Unison executable on the remote system) to the ssh
command used to invoke the remote server. The backslash is an escape character.
sshcmd xxx
This preference can be used to explicitly set the name of the ssh executable (e.g.,
giving a full path name), if necessary.
stream (Deprecated) When this preference is set, Unison will use an experimental streaming
protocol for transferring file contents more efficiently. The default value is true.
terse When this preference is set to true, the user interface will not print status
messages.
testserver
Setting this flag on the command line causes Unison to attempt to connect to the
remote server and, if successful, print a message and immediately exit. Useful for
debugging installation problems. Should not be set in preference files.
times When this flag is set to true, file modification times (but not directory modtimes)
are propagated.
ui xxx This preference selects either the graphical or the textual user interface. Legal
values are graphic or text. Because this option is processed specially during
Unison's start-up sequence, it can only be used on the command line. In preference
files it has no effect. If the Unison executable was compiled with only a textual
interface, this option has no effect. (The pre-compiled binaries are all compiled
with both interfaces available.)
unicode xxx
When set to true, this flag causes Unison to perform case insensitive file
comparisons assuming Unicode encoding. This is the default. When the flag is set to
false, Latin 1 encoding is assumed (this means that all bytes that are not letters
in Latin 1 encoding will be compared byte-for-byte, even if they may be valid
characters in some other encoding). When Unison runs in case sensitive mode, this
flag only makes a difference if one host is running Mac OS X. Under Mac OS X, it
selects whether comparing the filenames up to decomposition, or byte-for-byte.
version
Print the current version number and exit. (This option only makes sense on the
command line.)
watch Unison uses a file watcher process, when available, to detect filesystem changes;
this is used to speed up update detection. Setting this flag to false disables the
use of this process.
xattrignore xxx
Preference -xattrignore namespec causes Unison to ignore extended attributes with
names that match namespec. This can be used to exclude extended attributes that
would fail synchronization due to lack of permissions or technical differences at
replicas. The syntax of namespec is the same as used for path specification
(described in Section “Path Specification” in the manual); prefer the Path and Regex
forms over the Name form. The pattern is applied to the name of extended attribute,
not to path. On Linux, attributes in the security and trusted namespaces are ignored
by default (this is achieved by pattern Regex !(security|trusted)[.].*); also
attributes used to store POSIX ACL are ignored by default (this is achieved by
pattern Path !system.posix_acl_*). To sync attributes in one or both of these
namespaces, see the xattrignorenot preference. Note that the namespace name must be
prefixed with a "!" (applies on Linux only). All names not prefixed with a "!" are
taken as strictly belonging to the user namespace and therefore the "!user." prefix
is never used.
xattrignorenot xxx
This preference overrides the preference xattrignore. It gives a list of patterns
(in the same format as xattrignore) for extended attributes that should not be
ignored, whether or not they happen to match one of the xattrignore patterns. It is
possible to synchronize only desired attributes by ignoring all attributes (for
example, by setting xattrignore to Path * and then adding xattrignorenot for
extended attributes that should be synchronized. On Linux, attributes in the
security and trusted namespaces are ignored by default. To sync attributes in one or
both of these namespaces, you may add an xattrignorenot pattern like Path
!security.* to sync all attributes in the security namespace, or Path
!security.selinux to sync a specific attribute in an otherwise ignored namespace. A
pattern like Path !system.posix_acl_* can be used to sync POSIX ACLs on Linux. Note
that the namespace name must be prefixed with a "!" (applies on Linux only). All
names not prefixed with a "!" are taken as strictly belonging to the user namespace
and therefore the "!user." prefix is never used.
xattrs When this flag is set to true, the extended attributes of files and directories are
synchronized. System extended attributes are not synchronized.
xferbycopying
When this preference is set, Unison will try to avoid transferring file contents
across the network by recognizing when a file with the required contents already
exists in the target replica. This usually allows file moves to be propagated very
quickly. The default value is true.
ROOTS
A replica’s root tells Unison where to find a set of files to be synchronized, either on the
local machine or on a remote host. For example,
relative/path/of/root
specifies a local root relative to the directory where Unison is started, while
/absolute/path/of/root
specifies a root relative to the top of the local filesystem, independent of where Unison is
running. Remote roots can begin with ssh:// to indicate that the remote server should be
started with ssh(1):
ssh://remotehost//absolute/path/of/root
ssh://user@remotehost/relative/path/of/root
If the remote server is already running (in the socket mode), then the syntax
socket://remotehost:portnum//absolute/path/of/root
socket://remotehost:portnum/relative/path/of/root
socket://[IPv6literal]:portnum/path
is used to specify the hostname and the port that the client Unison should use to contact
it. Syntax
socket://{path/of/socket}//absolute/path/of/root
socket://{path/of/socket}/relative/path/of/root
is used to specify the Unix domain socket the client Unison should use to contact the
server.
The syntax for roots is based on that of URIs (described in RFC 2396). The full grammar is:
replica ::= [protocol:]//[user@][host][:port][/path]
| path
protocol ::= file
| socket
| ssh
user ::= [-_a-zA-Z0-9]+
host ::= [-_a-zA-Z0-9.]+
| \[ [a-f0-9:.]+ zone? \] IPv6 literals (no future format).
| { [^}]+ } For Unix domain sockets only.
zone ::= %[-_a-zA-Z0-9~%.]+
port ::= [0-9]+
When path is given without any protocol prefix, the protocol is assumed to be file:. Under
Windows, it is possible to synchronize with a remote directory using the file: protocol over
the Windows Network Neighborhood. For example,
unison foo //host/drive/bar
synchronizes the local directory foo with the directory drive:\bar on the machine host,
provided that host is accessible via Network Neighborhood. When the file: protocol is used
in this way, there is no need for a Unison server to be running on the remote host. However,
running Unison this way is only a good idea if the remote host is reached by a very fast
network connection, since the full contents of every file in the remote replica will have to
be transferred to the local machine to detect updates.
PATHS
A path refers to a point within a set of files being synchronized; it is specified relative
to the root of the replica. Formally, a path is just a sequence of names, separated by /.
Note that the path separator character is always a forward slash, no matter what operating
system Unison is running on. The empty path (i.e., the empty sequence of names) denotes the
whole replica.
PATH SPECIFICATION
Several Unison preferences (e.g., ignore/ignorenot, follow, sortfirst/sortlast, backup,
merge, etc.) specify individual paths or sets of paths. These preferences share a common
syntax based on regular expressions. Each preference is associated with a list of path
patterns; the paths specified are those that match any one of the path pattern.
Each pattern can have one of three forms. The most general form is a Posix extended regular
expression introduced by the keyword Regex. (The collating sequences and character classes
of full Posix regexps are not currently supported.)
Regex regexp
For convenience, three other styles of pattern are also recognized:
Name name
matches any path in which the last component matches name,
Path path
matches exactly the path path, and
BelowPath path
matches the path path and any path below. The name and path arguments of the latter forms of
patterns are not regular expressions. Instead, standard “globbing” conventions can be used
in name and path:
- a * matches any sequence of characters not including / (and not beginning with ., when
used at the beginning of a name)
- a ? matches any single character except / (and leading .)
- [xyz] matches any character from the set {x, y, z}
- {a,bb,ccc} matches any one of a, bb, or ccc. (Be careful not to put extra spaces after
the commas: these will be interpreted literally as part of the strings to be matched!)
The path separator in path patterns is always the forward-slash character “/” — even when
the client or server is running under Windows, where the normal separator character is a
backslash. This makes it possible to use the same set of path patterns for both Unix and
Windows file systems.
A path specification may be followed by the separator “ -> ” itself followed by a string
which will be associated to the matching paths:
Path path -> associated string
Not all pathspec preferences use these associated strings but all pathspec preferences are
parsed identically and the strings may be ignored. Only the last match of the separator
string on the line is used as a delimiter. Thus to allow a path specification to contain the
separator string, append an associated string to it, even if it is not used. The associated
string cannot contain the separator string.
PROFILES
A profile is a text file that specifies permanent settings for roots, paths, ignore
patterns, and other preferences, so that they do not need to be typed at the command line
every time Unison is run. Profiles should reside in the .unison directory on the client
machine. If Unison is started with just one argument name on the command line, it looks for
a profile called name.prf in the .unison directory. If it is started with no arguments, it
scans the .unison directory for files whose names end in .prf and offers a menu (when using
the graphical user interface; for the text interface, you have to use the -i option). If a
file named default.prf is found, its settings will be used as the default preferences.
To set the value of a preference p permanently, add to the appropriate profile a line of the
form
p = true
for a boolean flag or
p = <value>
for a preference of any other type. Whitespaces around p and the value are ignored. A
profile may also include blank lines and lines beginning with #; both are ignored.
When Unison starts, it first reads the profile and then the command line, so command-line
options will override settings from the profile.
TERMINATION
When not synchronizing continuously, the text interface terminates when synchronization is
finished normally or due to a fatal error occurring.
In the text interface, to interrupt synchronization before it is finished, press Ctrl-C (or
send signal SIGINT or SIGTERM). This will interrupt update propagation as quickly as
possible but still complete proper cleanup. If the process does not stop even after pressing
Ctrl-C then keep doing it repeatedly. This will bypass cleanup procedures and terminates the
process forcibly (similar to SIGKILL). Doing so may leave the archives or replicas in an
inconsistent state or locked.
When synchronizing continuously (time interval repeat or with filesystem monitoring),
interrupting with Ctrl-C or with signal SIGINT or SIGTERM works the same way as described
above and will additionally stop the continuous process. To stop only the continuous process
and let the last synchronization complete normally, send signal SIGUSR2 instead.
ENVIRONMENT
UNISON Unison stores a variety of information in a private directory on each host. If the
environment variable UNISON is defined, then its value will be used as the path for
this directory. This can be just a name, or a path. If UNISON is not defined, then
the directory depends on which operating system you are using. In Unix, the default
is to use $HOME/.unison. In Windows, if the environment variable USERPROFILE is
defined, then the directory will be $USERPROFILE\.unison; otherwise, it will be
c:\.unison. On macOS, $HOME/.unison will be used if it is present, but
$HOME/Library/Application Support/Unison will be created and used by default.
UNISONLOCALHOSTNAME
The function that finds the canonical hostname of the local host (which is used, for
example, in calculating the name of the archive file used to remember which files
have been synchronized) normally uses the gethostname operating system call.
However, if the environment variable UNISONLOCALHOSTNAME is set, its value will be
used instead. This makes it easier to use Unison in situations where a machine’s
name changes frequently (e.g., because it is a laptop and gets moved around a lot).
UNISONBACKUPDIR
When backups are stored centrally, the directory used to hold them is controlled by
the preference backupdir and the environment variable UNISONBACKUPDIR. If both are
specified then the environment variable overrides the preference. If neither of
these are set, then the directory $UNISON/backup is used (see environment variable
UNISON above).
PAGER Used by the text interface as the pager when displaying the differences between
changed files.
NO_COLOR
If the environment variable NO_COLOR is set then Unison's text interface will not
produce any color output by default. The color preference overrides this environment
variable.
FILES
~/.unison
Unison stores a variety of information in a private directory on each host. This is
the default path of this private directory. This path may be changed by the UNISON
environment variable.
~/.unison/*.prf
Profile files. Each profile is stored in a file named profilename.prf.
~/.unison/ar*
~/.unison/tm*
~/.unison/sc*
Main and temporary archive files. These files may be deleted if you know what you
are doing. Deleting an archive file is equivalent to using the -ignorearchives
option.
~/.unison/fp*
Fingerprint cache files. These files may be safely deleted. Keep in mind that
deleting a fingerprint cache file means that any unsynchronized changes must be
scanned again. Depending on your replicas, this may mean scanning gigabytes of file
contents.
~/.unison/lk*
Lock files indicating a running Unison process. These files may be deleted if you
are careful and know that there is no Unison process currently running. Deleting a
lock file is equivalent to using the -ignorelocks option.
EXAMPLES
Synchronize two local directories
unison path/to/dir1 /dir2
This command synchronizes two local directories using the default options. Default
options are defined by Unison and can be overridden by user in a profile called “default”,
which is by default stored in file ~/.unison/default.prf
Synchronize a local and a remote directory
unison local/dir ssh://user@host//absolute/path
This command synchronizes a local directory (here specified by a relative path) and a
remote directory (here specified by an absolute path) using ssh(1) and the default options
(see example above).
Synchronize with all options specified in a profile
unison profilename
This command reads all the options from the profile named “profilename” and synchronizes
according to those options.
Synchronize with options specified in a profile and roots on command line
unison profilename /path/to/dir ssh://host/path/on/server
This command reads all options from the profile named “profilename” with only the roots
specified on the command line. Roots must not be specified in the profile as the roots
from command line will not override roots in the profile, rather append to the list of
roots.
Synchronize automatically
unison -batch /path/to/dir ssh://host/path/on/server
This command synchronizes all non-conflicting changes automatically, once.
Synchronize continuously
unison -repeat watch /path/to/dir ssh://host/path/on/server
This command first fully synchronizes the roots and then remains dormant, waiting for any
file changes within either root and then automatically synchronizes these changes. This
also works in a profile (repeat = watch). If the filesystem monitoring helper program is
not available or not desired for other reasons, it is possible to make Unison synchronize
repeatedly with a defined time interval:
unison -repeat 60 /path/to/dir ssh://host/path/on/server
This command synchronizes every 60 seconds. Using -repeat implies -batch.
Currently, continuous synchronization is not possible when using the GUI.
DIAGNOSTICS
When running in the textual mode, Unison returns an exit status, which describes whether,
and at which level, the synchronization was successful. The exit status could be useful when
Unison is invoked from a script. Currently, there are four possible values for the exit
status:
0 successful synchronization; everything is up-to-date now.
1 some files were skipped, but all file transfers were successful.
2 non-fatal failures occurred during file transfer.
3 a fatal error occurred, or the execution was interrupted.
The graphical interface does not return any useful information through the exit status.
COMPATIBILITY
If you are using Unison versions ≥ 2.52 on all machines, you do not have to do anything
extra for compatibility.
Historically (versions < 2.52), Unison versions had to be matched relatively exactly for
them to work together. Additionally, the version of compiler used to build Unison also had
significant relevance for compatibility.
As of version 2.52, Unison has a degree of backward and forward compatibility. This means
three things. First, it is possible for local and remote machines to run a different version
of Unison. Second, it is possible for local and remote machines to run a version (same or
different) of Unison built with a different version of compiler. Lastly, it is possible to
upgrade Unison on the local machine and keep the existing archive.
For more information on co-existence of versions < 2.52 and ≥ 2.52, see
https://github.com/bcpierce00/unison/wiki/2.52-Migration-Guide
SEE ALSO
There is a full user manual (pdf, html and txt) included with Unison and available online.
Depending on your operating system, this manual may have been installed at
/usr/share/doc/unison/ or a similar location. The manual can also be read in the GUI (look
in the Help menu) or on the command line by unison -doc all (you probably want to pipe the
output to a pager).
https://github.com/bcpierce00/unison
https://www.cis.upenn.edu/~bcpierce/unison/