Taking Screenshots with Linux
Follow @ggarronFind here how to take Screen Shots with Linux, could help you specially if you like to write Linux tutorials
If you like to write tutorial, or need a screen shot for any homework or job, the Linux Operating System gives you some very good resources to have this task done.
The Gimp
With Gimp you have to go to:
File->Acquire->Screeshot
and you will get a dialog box like this

As you see you have three options:
- Take Screenshot of a singe window: This will make your cursor be a thick cross, and you can select the window to take the screenshot of
- Take a Screenshot of the entire screen: This will take a screenshot of the entire screen
- Select a region to grab: This will make the cursor into a cross and you can grab a region of the screen to take a screenshot of it
Gnome
If you use Gnome you can just press PrtSC (Print Screen) key, this will take a screen shot of the whole screen, you can only choose where to save the screenshot, the size will be the size of you screen, I mean the same resolution.
Imagemagick
First install the software:
Fedora / Centos
yum install imagemagick
Debian / Ubuntu
sudo apt-get install imagemagick
Then you can use one of its tools, which is import
Take a screenshot of the full screen
import -window root screenshot.jpg
If you need some time to arrange the screen for your screenshot.
Updated, thanks to a friend of the blog
import -pause 3 -window root screenshot.jpg
This will give you 3 seconds before the screen shot is taken.
Take a screenshot of just a region of the screen
import screenshot.jpg
This will make your cursor looks like a cross and you can select the region of the screen to take the screenshot, here you can also use the sleep command.
Vmware
If you are using VMware you can select
vm->capture screen
And you will see a dialog box like this:

And you will take a screenshot of the whole screen of the vmware screen.
Two more tips
I will show you now two more very useful when managing screenshots.
Crop images with gimp

Select the circled tool, and use it to select the region of the image you want to crop.
Changing the size of the image, and creating thumbnails
If you need to resize your images, or create thumbnails for them you can use imagemagick once again:
convert -resize 150x imputfile.jpg outputfile.jpg
This will resize your image to 640 to anything the imputfile.jpg and save it as outputfile.jpg, it is always better to only specify one of the sizes to maintain the proportion of the image.
If you want to convert a lot of images at the same time, you can use a trick I learned from my friend of bashcurescancer
find . -type f -name '*.png' -exec convert -resize 640x {} {} \;
This way you will find files ending in .png and resize them to 640x size, the output files will be named the same as the input ones, take care with this if you do not want to loose the original files.