How can I check if a program exists from a Bash script?

Question

How would I validate that a program exists, in a way that will either return an error and exit, or continue with the script?

It seems like it should be easy, but it\

Answer 1

This will tell according to the location if the program exist or not:

    if [ -x /usr/bin/yum ]; then
        echo "This is Centos"
    fi