How to write binary data in Bash

Question

Let us say there is a variable in bash script with value \"001\" how can i write this binary data into a file as bits (as \"001\" not \"1\") echo writes it as string but i w

Answer 1

Most often you want to write a pattern (for instance a 32 bit pattern).

# Write 32 bits 5 times to a file 
for i in {1..5}
do
   printf '\x12\x34\xAC\xCD' >> binaryfile.bin
done

Another example:

for i in {1..255}
do
    hx=$( printf "%x" $i )
    output="\x$hx\x00\x00\x00"
    printf "%b" $output >> binaryfile.bin 
done