Is it possible to "print to jpeg" (instead "print to PDF")?

[Freelance Physicist]

Nice, I didn't know about the selection tool, I know "Print Screen" will get the whole screen and "ALT-Print Screen" will get the current window, but I didn't know about the selection tool. Is there a keyboard shortcut?

No, but you can create one. Go to System->Preferences->Keyboard shortcuts and click on Add, then fill in the boxes. For Name, I use "Take a screenshot with options" and for Command, use

gnome-screenshot --interactive

After clicking Apply, scroll to the bottom of the list and click on Disabled to assign a shortcut key (I used Ctrl+Shift+PrintScreen).

[ruipedroca]

Nice, I didn't know about the selection tool, I know "Print Screen" will get the whole screen and "ALT-Print Screen" will get the current window, but I didn't know about the selection tool. Is there a keyboard shortcut?

Give credut to WorMzy also, he pointed it out!

You're right!
Thanks WorMzy!

[l0co]

Try printing to the pdf and then try

convert filename.pdf filename.jpg

Sometimes is also useful to convert pdf into a single image file. For this use:

convert -append filename.pdf filename.jpg