update /Users/sjs/.rbenv/shims:/usr/local/bin:/usr/local/android/sdk/platform-tools:/usr/local/android/sdk/tools:/Users/sjs/.rbenv/bin:/Users/sjs/bin:/usr/sbin:/sbin:/usr/bin:/bin:/opt/X11/bin:/Applications/Xcode.app/Contents/Developer/usr/bin
attach to screens automatically
add irb_history to .gitignore