Return to readline version 6.x in Homebrew to fix Postgresql?

I'm no Homebrew expert but I think it has "upgraded" me from readline version 6.x to 7.0 sometime after [9/15/16][1]:

eat@eric-macbook:Homebrew$ brew info readline
readline: stable 7.0 (bottled) [keg-only]
Library for command-line editing

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/usr/local/Cellar/readline/7.0 (45 files, 2M)

This has caused headaches for my 9.4.5 Homebrew version of Postgresql (I need the older 9.4 for comparability reasons):

eat@eric-macbook:~$ psql --version
dyld: Library not loaded: /usr/local/opt/readline/lib/libreadline.6.dylib
Referenced from: /usr/local/Cellar/postgresql/9.4.5/bin/psql
Reason: image not found
Trace/BPT trap: 5

Unfortunately I can't find a 6.x version of readline on Homebrew to revert to - only 7.0 seems to be available(?).

My question is twofold:

- Is the the readline version mismatch the cause of my postgres/psql problem?
- If so, how do I return to 6.x with Homebrew to correct the problem?

Thank you in advance!


[1]:

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Just reinstall `postgresql94` package, the PostgreSQL 9.4 will use the new `readline` package:

brew reinstall postgresql94

To answer the specific question.

You can switch between version of installed brew packages which are still around locally as explained in this question:

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To downgrade to readline 6.x the following command worked for me:

brew switch readline 6.3.8

I was able to overcome this with a blanket `brew upgrade` (upgrade all brew-managed packages).

For people coming from Rails with this issue you can just add the readline gem and run `bundle install`.

gem 'rb-readline' #Fixed readline error

If you would use Sam Kah Chiin's solution, you can ignore the 404.


Apply the extra change so it would work on new macOS:

diff --git a/Formula/readline.rb b/Formula/readline.rb
index 08d3728..d67e5e4 100644
--- a/Formula/readline.rb
+++ b/Formula/readline.rb
@@ -16,7 +16,7 @@ class Readline < Formula
sha256 "c129333634dd00ab2267ae9c531fca1f5cc50dd519ed3399918289fdfdf2663b" => :lion
end

- keg_only :shadowed_by_osx, <<-EOS.undent
+ keg_only :shadowed_by_macos, <<~EOS
OS X provides the BSD libedit library, which shadows libreadline.
In order to prevent conflicts when programs look for libreadline we are
defaulting this GNU Readline installation to keg-only.

Do `sudo update_dyld_shared_cache` at the end

NOTE: This answer might be outdated due to the changes in the branch (as reported by Andrew, the commit disappear)

To those who still facing this issue but cannot download the readline 6.3.8 from the homebrew package. You can try this solution. (Refer from [here][1])


# Uninstall this incompatible version
brew uninstall readline

# Go to the local clone of homebrew-core
cd $(brew --prefix)/Homebrew/Library/Taps/homebrew/homebrew-core

# Move to the homebrew-core revision that had 6.3.8
git checkout 35fed817726f61a9d40c8420582f6fde59eb5f14

# Re-install readline
brew reinstall readline

# Switch back to HEAD
git checkout master

# Pin readline so this can't happen again
brew pin readline


[1]:

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