shell if say yes
#!/bin/bash
# ...
# in the middle of some long script
# obtain a response from the user
# ...
echo "Are you happy to proceed? [y,n]"
read input
# did we get an input value?
if [ "$input" == "" ]; then
echo "Nothing was entered by the user"
# was it a y or a yes?
elif [[ "$input" == "y" ]] || [[ "$input" == "yes" ]]; then
echo "Positive response: $input"
# treat anything else as a negative response
else
echo "negative response: $input"
fi