• npm
• Homebrew
• rbenv
• bundler

# Show outdated packages
$ npm outdated -g --depth=0.
$ npm update -g
$ npm install -g outdated_package

$ brew update
$ brew upgrade
$ brew list --versions
$ brew services [[start|stop|restart]] postgresql

Packages:

• vnstat
• watch
• tree
• tmux
• wrk
• dopewars
• ffmpeg
• osquery
• fsql

In case a package is problematic/non-functional, switch back to another version:

$ brew info postgresql
$ brew switch postgresql 9.5.3

# Error: Another active Homebrew process is already in progress. 
# Please wait for it to finish or terminate it to continue.
$ rm /usr/local/var/homebrew/locks/*

# (PG::ConnectionBad)
# Is the server running locally and accepting
# connections on Unix domain socket "/tmp/.s.PGSQL.5432"?
$ cat /usr/local/var/postgres/server.log
$ brew services restart postgresql
$ brew switch postgresql 9.5.3

# List locally installed Rubies
$ rbenv known

$ rbenv update

# List available Rubies
$ rbenv install -l

# Uninstall all gems
$ for i in `gem list --no-versions`; do gem uninstall -aIx $i; done

# List
$ gem list [--no-versions]

# Update all gems
$ gem update

To easily reinstall gems when moving from one Ruby to another:

$ echo "source \"https://rubygems.org\"" > Gemfile
$ for i in `gem list --no-versions`; do echo "gem '$i'" >> Gemfile; done