How to install unison on Ubuntu 17.04

Once it is done, use the following command to update the newly added repository. 

root@linuxhelp:~# apt-get update
Hit:1 http://security.ubuntu.com/ubuntu zesty-security InRelease    
Hit:2 http://in.archive.ubuntu.com/ubuntu zesty InRelease                
Hit:3 http://in.archive.ubuntu.com/ubuntu zesty-updates InRelease        
Get:4 http://ppa.launchpad.net/eugenesan/ppa/ubuntu zesty InRelease [15.4 kB]
Hit:5 http://in.archive.ubuntu.com/ubuntu zesty-backports InRelease            
Hit:6 http://ppa.launchpad.net/js-reynaud/kicad-4/ubuntu zesty InRelease       
Get:7 http://ppa.launchpad.net/eugenesan/ppa/ubuntu zesty/main amd64 Packages [4,192 B]
Get:8 http://ppa.launchpad.net/eugenesan/ppa/ubuntu zesty/main i386 Packages [4,192 B]
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Get:8 http://ppa.launchpad.net/eugenesan/ppa/ubuntu zesty/main i386 Packages [4,192 B]
Get:9 http://ppa.launchpad.net/eugenesan/ppa/ubuntu zesty/main Translation-en [3,288 B]
Fetched 27.0 kB in 4s (6,278 B/s)                   
Reading package lists... Done

After updating the repositories, you can proceed with the installation of Unison by running the following command as it kick-starts the installation process. 

root@linuxhelp:~# apt-get install unison
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Suggested packages:
  unison-all
The following NEW packages will be installed:
  unison
0 upgraded, 1 newly installed, 0 to remove and 306 not upgraded.
Need to get 688 kB of archives.
After this operation, 2,345 kB of additional disk space will be used.
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Setting up unison (2.48.3-1ubuntu1) ...
update-alternatives: using /usr/bin/unison-latest-stable to provide /usr/bin/unison (unison) in auto mode
Processing triggers for doc-base (0.10.7) ...
Processing 1 added doc-base file...
Processing triggers for man-db (2.7.6.1-2) ...

If you want to check all the options available with Unison, you need to run the following command.

root@linuxhelp:~# unison -help
Usage: unison [options]
    or unison root1 root2 [options]
    or unison profilename [options]

Basic options: 
 -auto              automatically accept default (nonconflicting) actions
 -batch             batch mode: ask no questions at all
 -doc xxx           show documentation (' -doc topics'  lists topics)
 -fat               use appropriate options for FAT filesystems
 -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)
 -silent            print nothing except error messages
 -terse             suppress status messages
 -testserver        exit immediately after the connection to the server
 -times             synchronize modification times
 -version           print version and exit

Advanced options: 
 -addprefsto xxx    file to add new prefs to
 -addversionno      add version number to name of unison on server
 -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           keep backup copies of all files (see also ' backup' )
 -backupsuffix xxx  a suffix to be added to names of backup files
 -clientHostName xxx set host name of client
 -confirmbigdel     ask about whole-replica (or path) deletes (default true)
 -confirmmerge      ask for confirmation before committing results of a merge
 -contactquietly    suppress the ' contacting server'  message during startup
 -copymax n         maximum number of simultaneous copyprog transfers
 -copyonconflict    keep copies of conflicting files
 -copyprog xxx      external program for copying large files
 -copyprogrest xxx  variant of copyprog for resuming partial transfers
 -copyquoterem xxx  add quotes to remote file name for copyprog (true/false/default)
 -copythreshold n   use copyprog on files bigger than this (if > =0, in Kb)
 -debug xxx         debug module xxx (' all'  ->  everything, ' verbose'  ->  more)
 -diff xxx          set command for showing differences between files
 -dontchmod         when set, never use the chmod system call
 -dumbtty           do not change terminal settings in text UI
 -fastcheck xxx     do fast update detection (true/false/default)
 -fastercheckUNSAFE skip computing fingerprints for new files (experts only!)
 -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
 -halfduplex        force half-duplex communication with the server
 -height n          height (in lines) of main window in graphical interface
 -host xxx          bind the socket to this host name in server socket mode
 -ignorearchives    ignore existing archive files
 -ignorecase xxx    identify upper/lowercase filenames (true/false/default)
 -ignoreinodenumbers ignore inode number changes when detecting updates
 -ignorelocks       ignore locks left over from previous run (dangerous!)
 -immutable xxx     add a pattern to the immutable list
 -immutablenot xxx  add a pattern to the immutablenot list
 -key xxx           define a keyboard shortcut for this profile (in some UIs)
 -killserver        kill server when done (even when using sockets)
 -label xxx         provide a descriptive string label for this profile
 -links xxx         allow the synchronization of symbolic links (true/false/default)
 -log               record actions in logfile (default true)
 -logfile xxx       logfile name
 -maxbackups n      number of backed up versions of a file
 -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
 -merge xxx         add a pattern to the merge list
 -mountpoint xxx    abort if this path does not exist
 -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
 -numericids        don' t map uid/gid values by user/group names
 -prefer xxx        choose this replica' s version for conflicting changes
 -preferpartial xxx add a pattern to the preferpartial list
 -repeat xxx        synchronize repeatedly (text interface only)
 -retry n           re-try failed synchronizations N times (text ui only)
 -rootalias xxx     register alias for canonical root names
 -rsrc xxx          synchronize resource forks (true/false/default)
 -rsync             activate the rsync transfer mode (default true)
 -selftest          run internal tests and exit
 -servercmd xxx     name of unison executable on remote server
 -showarchive       show ' true names'  (for rootalias) of roots and archive
 -socket xxx        act as a server on a socket
 -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
 -sshargs xxx       other arguments (if any) for remote shell command
 -sshcmd xxx        path to the ssh executable
 -stream            use a streaming protocol for transferring file contents (default true)
 -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 (default true)
 -xferbycopying     optimize transfers using local copies (default true)

root@linuxhelp:~# unison -version
unison version 2.48.3