tr -s '4011' '|' <$x>> modified.txt

tr -d '13'  <modified1.txt>> $FILENAME

sed 's/o14//g' file

sed 's/f//' file

sed 's/

sed 's/^L

sed 's/^L//g' file

tr -d 'f' < file

perl -pe 's/f//g' file

perl -0pe 's/fs*/n/s' file

sed $'/f/,/./{/f/d;/./!d;}'