decodeURI.sh

#!/bin/bash
awk 'BEGIN { for (i=0;i<=16;i++) hex[sprintf("%X",i)]=i; }
{
    for (i=1;i<=length($0);i++) { 
        c=substr($0,i,1)
        if (c=="+") { printf (" "); }
        else if (c=="%") {
            printf ("%c",hex[substr($0,++i,1)]*16+hex[substr($0,++i,1)])
        }
        else { printf (c); }
    }
}'

encodeURI.sh

#!/bin/bash
cat /dev/stdin | od -t x | awk '{
    w=split($0,linedata," ");
    for (j=2;j<w+1;j++) {
        for (i=7;i>0;i=i-2) {
            if (substr(linedata[j],i,2) == "0d") {continue;}  // "\r"
            if (substr(linedata[j],i,2) == "0a") {printf "\n";continue;}  // "\n"
            if (substr(linedata[j],i,2) != "00") {printf "%" ;printf toupper(substr(linedata[j],i,2));}
        }
    }
}'