sed print 4

#!/bin/sed -nf

# Prints the line containing a regular expression and next 4 lines

# check if line matches regex
/foo/{
    # set hold space to 4
    x
    s/.*/4/
    x
    # print line and restart
    p
    d
}

# if no match, check whether hold space is between 1 and 4
x
/[1-4]/{
    # decrement integer in hold space
    y/1234/0123/
    x
    # print line and restart
    p
    d
}