Install Unison 2.48.4 on Mac OS X with Homebrew

I use Unison to sync code between my local machine and my dev servers. To sync between two servers, it requires that the same version of Unison be installed on both servers.

Now, this isn’t usually a big deal, because once you get Unison set up, it’s set up. But, I usually get a bit frustrated when setting up a new development machine and ensuring that it has the same Unison version as my remote server.

Most recently, I needed to get Unison 2.48.4 on my local Mac so that it matched my remote server. BUT, homebrew didn’t support Unison 2.48.4.

So, after getting some feedback from one of my coworkers, we came up with the following. Maybe you’ll find it helpful.

# Get rid of existing Unison
brew uninstall --force unison

# Checkout version of homebrew with Unison 2.48.4
cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core
git checkout 05460e0bf3ae5f1a15ae40315940b2d39dd6ac52 Formula/unison.rb

# Install
brew install --force-bottle unison

# Set homebrew-core back to normal
git checkout master
git reset HEAD .
git checkout -- .

NOTE: If you get error: fatal: reference is not a tree: 05460e0bf3ae5f1a15ae40315940b2d39dd6ac52 after running git checkout 05460e0bf3ae5f1a15ae40315940b2d39dd6ac52 Formula/unison.rb, we’ve been able to fix the issue by recloning homebrew-core. If you get the same error, you’ll want to add these steps before retrying starting at the git checkout 05460e0bf3ae5f1a15ae40315940b2d39dd6ac52 Formula/unison.rb command above.

cd /usr/local/Homebrew/Library/Taps/homebrew
rm -rf homebrew-core
git clone https://github.com/Homebrew/homebrew-core.git
cd homebrew-core

28 responses to “Install Unison 2.48.4 on Mac OS X with Homebrew”

Derek

January 22, 2019 at 10:06 am

Thank you!

Reply
Osk

January 24, 2019 at 7:34 am

This post has helped at least to automatticians to fix their unison environment. Thank you! It would have helped three probably, but I lost my faith in unison long ago.

Reply
1. Osk
  
  January 24, 2019 at 7:35 am
  
  s/to/two
  
  Reply
  1. Miguel Lezama
    
    May 31, 2021 at 4:11 pm
    
    make it three!
    
    Reply
Alexis

January 24, 2019 at 2:51 pm

YAAAAY

Reply
Rebecca Hum

February 1, 2019 at 11:55 am

Woohoo! Thank you!

Reply
S.S

February 12, 2019 at 4:10 pm

Were there any additional commands that needed to be run after git checkout master command?

Reply
1. Eric Binnion
  
  February 12, 2019 at 4:22 pm
  
  From memory, I don’t believe so. Are you running into an issue?
  
  Reply
  1. Steven Stratis
    
    February 12, 2019 at 4:32 pm
    
    Thanks for the reply. If I try to run git checkout 05460e0bf3ae5f1a15ae40315940b2d39dd6ac52 Formula/unison.rb
    I’m getting the error: fatal: reference is not a tree: 05460e0bf3ae5f1a15ae40315940b2d39dd6ac52
    
    Reply
    1. Eric Binnion
      
      February 12, 2019 at 7:03 pm
      
      What does it look like if you do the following commands in /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core?
      
      git status
      
      git remote -v
      
      Reply
      1. S.S
        
        February 12, 2019 at 8:19 pm
        
        Says that I’m up to date with master and that the remote origins are pointing to the github repo for fetch and push.
      2. Jeff
        
        February 28, 2019 at 11:59 am
        
        I’m experiencing this same exact problem as well.
    2. Eric Binnion
      
      February 28, 2019 at 12:24 pm
      
      Hi Steven �
      
      Working with Jeff, who commented below, we were able to replicate the issue and come up with a fix. I’ve updated the post with some updated commands.
      
      Hope this helps.
      
      Reply
      1. Jeff
        
        February 28, 2019 at 12:32 pm
        
        THANKS ERIC YOU’RE THE BEST! Works per the updated post.
Julian Vidal

May 27, 2019 at 2:34 pm

Thanks Eric!

FYI: My git checkout silently failed to overwrite the existing Formula/unison.rb file so I had to remove that before checking it out. If I didn’t, homebrew kept installing the latest version.

Reply
Paul Harrison

June 17, 2019 at 1:59 am

A less alarming way to fully clone homebrew-core is:

cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core

git fetch –unshallow

Reply
nbloomf

July 16, 2019 at 10:52 am

Thanks, Eric!

Reply
George Stephanis

July 22, 2019 at 3:02 pm

A couple enhancements I’ve found —

export HOMEBREW_NO_INSTALL_CLEANUP=1 in my .bashrc file ensures that homebrew keeps the old versions of stuff around instead of deleting them.

Also, brew uninstall --force unison can be swapped out for brew unlink unison — which will remove the unison alias but leave the other version in place so the old version can be installed.

After this is all done, you should have two versions of the unison binary available, if you need to be able to connect to multiple servers running different unisons.

… actually now that I think about it, the following may just work for everything:

cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core git fetch --unshallow brew list unison --versions brew switch unison 2.48.4_1

After the brew list unison --versions the version 2.48 may be available again? If not then do the git checkout stuff above

Reply
Jeroen

September 24, 2019 at 2:23 am

This has been super helpful, thanks a lot for posting this!

Reply
dukechem

October 3, 2019 at 12:43 pm

This comment also at https://gist.github.com/dukechem/ef5cb77d0b571eb0f794a4be821bd53c#gistcomment-3044805
Example below shows general method to find and install commits for other older or newer versions of unison, in this case, 2.48.15 …
It follows advice from https://medium.com/@schmijos/installing-old-homebrew-formulas-dc91de0c329c

Note: this is ok for simple binary bottles, like unison, with few, if any, dependencies. But dependencies quickly break things if you try such tricks to try to have something like both python versions 3.69 and 3.74: pip3 breaks for example as shown at https://gist.github.com/dukechem in python.rb per comments at https://gist.github.com/dukechem/ef5cb77d0b571eb0f794a4be821bd53c

cd /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core
git log master -- Formula/unison.rb ... commit f5755fe4ccecb63c669d633f804428267d3bf3d1 Author: BrewTestBot <brew-test-bot@googlegroups.com> Date: Tue Feb 20 12:46:06 2018 +0000 unison: update 2.48.15 bottle.

$ brew unlink unison
$ export HOMEBREW_NO_INSTALL_CLEANUP=1
$ brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/f5755fe4ccecb63c669d633f804428267d3bf3d1/Formula/unison.rb
==> Consider using brew extract unison ...!
This will extract your desired unison version to a stable tap instead of
installing from an unstable URL!

######################################################################## 100.0%
…
$ brew switch unison
unison installed versions: 2.48.4_1, 2.48.15, 2.51.2
“`

Reply
Dwain

October 22, 2019 at 4:35 am

Thank you, Eric!

Reply
Chris R

November 25, 2019 at 5:04 pm

Thank you for writing this up Eric! Worked a treat when I set up my new machine. ????

Reply
John

April 1, 2020 at 3:07 pm

Thank you Eric! This is still relevant in 2020… ran into the ‘not a tree’ issue, and the workaround steps worked perfectly.

Reply
1. Eric Binnion
  
  April 1, 2020 at 3:23 pm
  
  Wonderful! I’m glad it was helpful for you. Thank you for sharing. ?
  
  Reply
Thomas David Baker

April 21, 2020 at 11:40 pm

A+

Reply
Donncha O Caoimh

April 30, 2020 at 5:20 am

The work around didn’t work for me but installing it with this did:

brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/f5755fe4ccecb63c669d633f804428267d3bf3d1/Formula/unison.rb

I got the same git errors but after fixing them by cloning again it still installed the latest version of Unison. No idea why but glad something worked. Thanks Eric and everyone for contributing. 🙂

Reply
leason

January 23, 2021 at 7:35 am

Thank you, Eric. I�ve installed unison 2.48.4 on macOS 11.1 by your guide.

Reply
Timm

April 21, 2021 at 9:53 am

It seems that 2.48 can’t be fetched anymore.
The install command ends up trying to download from https://ghcr.io/v2/homebrew/core/unison/manifests/2.48.4_1, which returns a 404.
Is there a way to get over this? Can I force Homebrew to use another url?
Thanks for your help.

Reply

Install Unison 2.48.4 on Mac OS X with Homebrew

28 responses to “Install Unison 2.48.4 on Mac OS X with Homebrew”

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