Grab Android screenshot to computer via ADB

There are many ways to take a screen shot on Android device. One simple way to capture the screen on Galaxy Nexus is to simultaneously
press and hold Powerand Volume
Down buttons. The image will be saved in a "Screenshot" directory and accessible via Gallery.

Quite often, however, I need to copy the captured image over to my computer. Usually, I do this with

adb
pull

command, but if I'm going to use CLI to retrieve the file, why don't I take the screen shot with it as well?

One method is to use

screencap

command
via

adb shell

like so:

adb shell screencap -p /sdcard/screen.png
adb pull /sdcard/screen.png
adb shell rm /sdcard/screen.png

Not bad, but seems like there's some room for improvement.

Information provided by

screencap -h

indicates
that screen shot can be sent to stdout, but running

adb
shell screencap -p > screen.png

results in seemingly corrupt file.

Luckily, I wasn't the first person looking into this
issue. Apparently, adb shell is
performing an EOL (end-of-line) character conversion, from LF (line
feed, '\n', 0x0A)
toCR+LF (carriage return followed by line feed, '\r\n', 0x0D0A).

If that sounds familiar, that's because I've
dealt with this before. Unfortunately, this time we're working with binary data, so using

tr
-d '\r'

command to remove all 0x0D will
likely corrupt it by also removing bytes that aren't part of the 0x0D0A sequence.
We want to only remove carriage return characters when they are followed by a line feed.

The solution is to use sed search
and replace as follows:

adb shell screencap -p | sed 's/\r$//' > screen.png

Unfortunately, I found that sed fix
while works on Ubuntu doesn't work on OS X. This solution using perl handles
binary search and replace better:

adb shell screencap -p | perl -pe 's/\x0D\x0A/\x0A/g' > screen.png

Now we have a one-liner that grabs a screen shot from the Android device and stores directly on the computer executing the command. Beautiful.