You have to make the script executable via 'chmod' before execution. If the script file name is 'tomcat_killer.sh'
$ sudo chmod +x tomcat_killer.sh
then to create shortcut, rename the file to 'k' and copy to /usr/bin/
(or one of the another path in PATH variable)
$ sudo mv tomcat_killer.sh k
$ sudo cp k /usr/bin
now k
kills Tomcat.