At first, I have a very intresting link for you: http://linoleum.leapster.org/
If you have time, visit the site. It contains very much information about Linux and very much more.
man COMMAND
sed "s/ä/ae/g;s/ü/ue/g;s/ö/oe/g;s/ß/ss/g" FILENAME_OLD > FILENAME_NEW
grep -Rn "STRING" *
xset b off