I ran your script in with a trace on to reproduce the problem. Here's what I saw:
$ sh -x hmm.sh
+ echo 'Is this for GH 3 part? yes/no'
Is this for GH 3 part? yes/no
+ read GH_answer
+ echo yes
+ '[yes' = 'yes]'
hmm.sh: line 7: [yes: command not found
Line 7 (after I added a sh-bang line) is:
if ["$GH_answer" = "yes"] ; then
I correct that by using white space, like so:
if [ "$GH_answer" == "yes" ] ; then
You'll need to do the same in a couple other places in your script as well.