Be sure to give it the execution permission.
cd ~/the/script/folder
chmod +x ./startup.sh
This will give exec permission to user, group and other, so beware of possible security issues. To restrict permission to a single access class, you can use:
chmod u+x ./startup.sh
This will grant exec permission only to user
For reference
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…