sed

extract lines

• -n = no stdout

sed -n '2p' <file>              # print 2nd line
sed -n '10,33p' <file>          # line 10 up to line 33
sed -n '1p;3p' <file>           # line 1 AND 3
sed -n '2,$p' <file>            # line 2 to the END

line /find/replace/

sed 's/..$//' <input.txt> > <output.txt>      # delete last 2 characters from each line

EOF