When I first use Ubuntu linux I was looking for a suitable and powerful texteditor for web development and I found many tools out there, and I forgot to try the default text editor that comes by default with linux , the gedit.
By default when you open gedit for the first time you will feel suck for the current customisation, but when you start to play with it's tools you will feel great

First open it by : Application >> Accessories >> gedit .

how to customise gedit

from Edit menu click preferences and from the view tab

1. Check display line number
2. Check highlight current line
3. Play with other options to discover them

from the view tab

• Set the tab indentation number as you like , I set it 4.
• Check enable automatic indentation