Check PostgresSQL version

psql --version

That's it!

Problem uploading image using MiniMagick gem in OSX

Rails gave the following error when saving ActiveRecord object with photo.

Validation failed: Photo Failed to manipulate with MiniMagick, maybe it is not an image? Original Error: MiniMagick::Invalid

After some digging, realized that my ImageMagick couldn't handle JPEG files. To be sure do the following:

convert -list configure

You should be able to see "jpeg" as one of the entries in "DELEGATES". If not, do the following:

brew remove jpeg
brew remove imagemagick
brew install jpeg
brew install imagemagick

References:
http://stackoverflow.com/questions/10810356/carrierwave-error-msg-failed-to-manipulate-with-minimagick-maybe-it-is-not-an http://stackoverflow.com/questions/5624778/imagemagick-jpeg-decode-delegate-missing-with-os-x-homebrew-install

Fix OSX in built iSight camera not detected

sudo killall VDCAssistant

That's it!

Set up canonical url for A/B test page variations

Say you have 2 page variations for an A/B test. Page A (original) - /home Page B (variation) - /home_variation In order for Google spiders to only pick up contents in Page A since it has already been crawled and SEO-ed and we don't want Page B to affect SEO rankings, we need to specify in Page B that the url to Page A is canonical, ie. the main url.

Export queried data from MySQL in bash command line

SELECT distinct(users.email), users.firstname INTO OUTFILE '~/Downloads/users.csv' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\"' FROM users;

Send/write code in Gmail emails

Use this chrome extension to write the code snippet in Markdown, toggle convert snippet to HTML and send. Win! https://chrome.google.com/webstore/detail/markdown-here/elifhakcjgalahccnjkneoccemfahfoa

Checkout version of a file in previous git commit

# This rolls back the diff of the file in the git commit
git checkout COMMIT_SHA FILE

# Commit the file modification (rolled back diff)
git add FILE
git commit -m "Check out previous version of file."