Step by step solution

Screencapture: Kazam:

sudo add-apt-repository ppa:and471/kazam-daily-builds
sudo apt-get update
sudo apt-get install kazam

ffmpeg:

sudo add-apt-repository ppa:jon-severinsson/ffmpeg

gifsicle:

sudo apt-get install gifsicle

Using:

1. Kazam capture and Save (with or without screenkey)

2. Crop:

   ffmpeg -i rst_quick_start.mp4 -vf "crop=790:720:320:250"  rst_quick_crop.mp4
   

3. ffmpeg convert to gif:

   # -t duration -r fps -s size -y (no ask overwrite)
   ffmpeg -y -i autotype.mp4 -t 48 -r 12 -pix_fmt rgb24 out.gif
   

4. gifsicle resize gif:

   gifsicle --delay=5 --loop out.gif > anim.gif
   

All in one solution

This one is much better if only need gif format.

http://askubuntu.com/questions/107726/how-to-create-animated-gif-images-of-a-screencast

sudo add-apt-repository ppa:fossfreedom/byzanz
sudo apt-get update && sudo apt-get install byzanz

window: mhc.sh

region: region.sh

(need https://github.com/lolilolicon/xrectsel)

Additional Tools

Screen Key:

sudo apt-get install screenkey