I have started remastering 5.1, modelling it after std. Anyways, I am having issues when I am updating from a text file list of packages or removing a list of packages from a text file. If it finds one it does not have, it will not go to the next line of the file. How can I tell apt and\or dpkg to ignore these and go to the next line?
I have googled for some argument I can thow into my string but have had no luck. Is this not possible?

some examples of what I am doing:

cat packagesiwant.txt | xargs apt-get install

cat packagesidontwant.txt | xargs dpkg --purge


Thanks!