Hex to Binary conversion in bash

Question

I'm trying to convert a series of bytes from hex to bin using bash. but I keep getting (seemingly random) "(standard_in) 1: syntax error" replies from the following code:

for j in c4 97 91 8c 85 87 c4 90 8c 8d 9a 83 81
do
        BIN=$(echo "obase=2; ibase=16; $j" | bc )
        echo $BIN
done

I did a similar thing with dec to bin, which works perfectly fine:

for i in {0..120}
do
        KEYBIN=$(echo "obase=2; ibase=10; $i" | bc)
        echo $KEYBIN
done

Does anyone have an idea why it works with decimal, but not with hex? In my opinion the syntax is pretty much the same (unless I'm missing something really hard.)

Solution 1

BC is a bit sensitive to case for hex values, change to uppercase and it should work

for j in C4 97 91 8C 85 87 C4 90 8C 8D 9A 83 81
do
        BIN=$(echo "obase=2; ibase=16; $j" | bc )
        echo $BIN
done

Output:

11000100
10010111
10010001
10001100
10000101
10000111
11000100
10010000
10001100
10001101
10011010
10000011
10000001

Solution 2

I came up with this:

printf converts to hex, xxd -r -p takes the ascii hex stream and makes it actual binary

dumping with hexdump to prove it worked...

printf "%016x" 53687091200 | xxd -r -p | hexdump -C

Solution 3

Here's the script I use:

#!/bin/bash
# SCRIPT:  hex2binary.sh
# USAGE:   hex2binary.sh Hex_Number(s)
# PURPOSE: Hex to Binary Conversion. Takes input as command line
#          arguments.
#####################################################################
#                      Script Starts Here                           #
#####################################################################
if [ $# -eq 0 ]
then
    echo "Argument(s) not supplied "
    echo "Usage: hex2binary.sh hex_number(s)"
else
    echo -e "\033[1mHEX                 \t\t BINARY\033[0m"
    while [ $# -ne 0 ]
    do
        DecNum=`printf "%d" $1`
        Binary=
        Number=$DecNum
        while [ $DecNum -ne 0 ]
        do
            Bit=$(expr $DecNum % 2)
            Binary=$Bit$Binary
            DecNum=$(expr $DecNum / 2)
        done
        echo -e "$Number              \t\t $Binary"
        shift
        # Shifts command line arguments one step.Now $1 holds second argument
        unset Binary
    done
fi