How to check that if a package is installed?

[S Mathias]

if [ "$(dpkg -l | awk '/tofrodos/ && /^ii/ {print $2}' | awk 
'/^tofrodos/')" == "" ]; then echo -e "error: no zip package 
detected\!\n\nYou could install it like e.g.: \"apt-get install 
tofrodos\""; fi









Is there a better way then this?



Thank you!




      
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