Linux - Debian - Bash - Installed Or Not Script from hynten@speed-mailer.com

add this 2 lines:
  echo $1 >> packages.txt
  uniq packages.txt > packages2.txt ; mv packages2.txt packages.txt 
  
the programs name is installed-or-not i have it in /bin
installed-or-not firefox                < adds firefox to list and if already there rm


Link To Download Script!
http://pastebin.com/5Nks717G

https://stackoverflow.com/questions/29669581/bash-script-check-from-file-if-package-is-installed