Install specific version of a Homebrew formula

brewv.sh

#!/bin/bash
#
# Install specific version of a Homebrew formula
#
# Usage: brewv.sh formula_name desired_version
#
# Notes:
# - this will unshallow your brew repo copy. It might take some time the first time 
#   you call this script
# - it will uninstall (instead of unlink) all your other versions of the formula.
#   Proper version management is out of scope of this script. Feel free to improve.
# - my "git log" uses less by default and when that happens it breaks the script 
#   Therefore we have the "--max-count=20" parameter. This might fail to find proper 
#   version if the one you wish to install is outside of this count.
#
# Author: Stanimir Karoserov ( demosten@gmail.com )
#

if [ "$#" -ne 2 ]; then
	echo "brewv.sh - installs specific version of a brew formula"
	echo "syntax: brewv.sh formula_name desired_version"
	echo "e.g.: brewv.sh swiftformat 0.39.1"
	exit 1
fi

git -C "$(brew --repo homebrew/core)" fetch --unshallow || echo "Homebrew repo already unshallowed"

commit=$(brew log --max-count=20 --oneline $1|grep $2| head -n1| cut -d ' ' -f1)
formula=$(brew log --max-count=20 --oneline $1|grep $2| head -n1| cut -d ':' -f1|cut -d ' ' -f2)

if [ -z ${commit} ] || [ -z ${formula} ]; then
	echo "No version matching '$2' for '$1'"
	exit 1
else 
	cd /usr/local/bin
	if [[ -e $formula ]]; then
		brew uninstall --force $1
	fi
	brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/$commit/Formula/$formula.rb

	echo "$1 $2 installed."
fi

Thank you for sharing your script, it's useful!

commit=$(brew log --max-count=20 --oneline $1|grep $2| head -n1| cut -d ' ' -f1)

grep $2 will use regex, so grep 3.1 will match 3*1, e.g.: 301, 311, it will also match git commit, not just formula version.

so,

• using grep -F, -F, --fixed-strings, Interpret PATTERNS as fixed strings, not regular expressions.
• grep -F " $2 "

the difference:

$ brew log --max-count=100 --oneline gradle | grep -F 3.1
6f91436288 gradle 4.3.1 (#20420)
7a6a40e0ac gradle 3.1 (#4982)

$ brew log --max-count=100 --oneline gradle | grep -F " 3.1 "
7a6a40e0ac gradle 3.1 (#4982)

I fork and updated it.

Nice to have it shared here, it gave me directions to my problem. Thank you @ox0spy for the grep tip.

I also want to mention this comment that helped me to figure out how to not uninstall the formula. My final solution will just upgrade the existing one.

I also made the max-lines an optional parameter together with the desired tap with default to homebrew core. Please check my fork =D

It worked. Thanks for sharing!