How to highlight text in PDF files in Linux [closed]

Solution 1:

You can use okular for that purpose. Be aware that it doesn't actually change the PDF. The annotations are stored in a separate file and can (only?) be displayed by okular.

screenshots

Solution 2:

Another option is Xournal (article on Wikipedia).

Solution 3:

Have you had a look at Jarnal as a rather cool general note taking tool (and its cross platform)?