Graphical debugger for bash
for debugging execute your script with:
bash -x <scriptname>gui debugger:http://bashdb.sourceforge.net/
Debugger for Bash version 3(Bourne again shell). Plugin for Eclipse. Will only work with shell script editor ShellEd.http://sourceforge.net/projects/basheclipse/
I haven't come across a visual debugger, but bashdb works quite well for debugging. You can set breakpoints, continue, print variables etc..
https://sourceforge.net/projects/bashdb/
Install via your distro's repositories. There is a quick-start guide here:http://www.rodericksmith.plus.com/outlines/manuals/bashdbOutline.html(first chapter takes only half an hour to read/try).