Bashdb is a utility that is similar to gdb, in that you can do things like set breakpoints at a line or at a function, print content of variables, you can restart script execution and more.
You can normally install it via your package manager, for example on Fedora:
sudo dnf install bashdb
Or get it from the homepage. Then you can run it with your script as a paramater:
bashdb <YOUR SCRIPT>
Here are a few commands to get you started:
l - show local lines, press l again to scroll down
s - step to next line
print $VAR - echo out content of variable
restart - reruns bashscript, it re-loads it prior to execution.
eval - evaluate some custom command, ex: eval echo hi
b <line num> set breakpoint on some line
c - continue till some breakpoint
i b - info on break points
d <line #> - delete breakpoint at line #
shell - launch a sub-shell in the middle of execution, this is handy for manipulating variables
For more information, I recommend consulting the manual: http://www.rodericksmith.plus.com/outlines/manuals/bashdbOutline.html
See also homepage: