How to not update homebrew automatically when brew install some packages?

Question

I installed python3 with homebrew on my Mac. However, the latest Python3.6 cannot work well with some packages, so I decide to roll back to the 3.5.2.

Since homebrew/versions has been deprecated，I checkout the commit in the directory: /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula

git log python3.rb

There

commit ec545d45d4512ace3570782283df4ecda6bb0044
Author: BrewTestBot <[email protected]>
Date:   Tue Oct 11 06:42:06 2016 +0100

      python3: update 3.5.2_3 bottle.

Then

git chekcout ec545 
brew install python3

However, it seems that homebrew update itself automatically I run $brew install [Formula]

➜  Formula git:(ec545d4) brew install python3
    Updating Homebrew...

How to not update homebrew automatically when brew install some packages? Or how to install python 3.5.2 with homebrew?

Answer 1

Answer for the first question, How to not update homebrew automatically when brew install some packages?

1. hack code solution:

   vim /usr/local/Homebrew/Library/Homebrew/brew.sh

   Add return after line

   update-preinstall() {

   to:

   update-preinstall() {
   return
   

2. environment variable solution:

   export HOMEBREW_NO_AUTO_UPDATE=1

   or

   export HOMEBREW_AUTO_UPDATING=0

   or

   export HOMEBREW_UPDATE_PREINSTALL=0

if U will always work, add it to .bash_profile