Take retina screenshots on non-retina Macs

A few minutes ago, I posted about using curl to inspect HTTP headers, and I included a screenshot of the terminal window. Then I opened the page on my Retina iPad: the screenshot looked awful, to say the least.

Retina display icon

So I googled a bit and found this awesome Gist by Simone Manganelli, that shows the commands needed to enable “HiDPI” modes on regular Macs. These modes use four pixels on the screen for each “logical” pixel, just like Retina screens do. This will of course greatly decrease the available screen real estate, but on my 2560×1440 27-inch monitor it’s not much of an issue, not for the time needed to take a screenshot, at least.

The first command will make these mode available for selection from System Preferences/Display, the second will remove them. Note that you need to log out and then back in after issuing the first command to see the newly added resolutions.

Using this trick I was able to capture a much higher res screenshot, that definitely looks better on Retina screens.

Check the headers sent by a web server using curl

If you ever wanted to easily and quickly check the headers sent by any web server you can do it with curl. It comes preinstalled in OS X as well as in many Linux distributions, and it makes this operation really straightforward.

Curl in action showing HTTP headers

Just launch

curl -I http://somesite.com/

and you’ll get every response header sent by the site. Easy, huh?