urlencode.awk

#!/usr/bin/awk

BEGIN {
    for (i = 0; i <= 255; i++) {
	ord[sprintf("%c", i)] = i
    }
}

function escape(str, c, len, res) {
    len = length(str)
    res = ""
    for (i = 1; i <= len; i++) {
	c = substr(str, i, 1);
	if (c ~ /[0-9A-Za-z]/)
	    res = res c
	else
	    res = res "%" sprintf("%02X", ord[c])
    }
    return res
}

{ print escape($0) }