oneliners

# Program 1 -- print the third column of each line
perl -pe '$_ =perl -ane 'print $F[2], "\n"'

# Program 2 -- treat each line as a number and sum all lines
perl -pe '$\+=$_}{'

# Program 3 -- print an empty line after each line
perl -pe '$\="\n"'

# Program 4 -- number the lines
perl -pe '$_="$.$_"'

# Program 5 -- print everything between START and END
perl -ne 'print if /START/../END/'