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

You can write arbitrary bytes in hex or octal with:

printf '\x03' > file   # Hex
printf '\003' > file   # Octal

If you have binary, it's a bit tricker, but you can turn it into octal with:

printf '%o\n' "$((2#00000011))"

which of course can be nested in the above:

binary=00000011
printf "\\$(printf '%o' "$((2#$binary))")" > file

Note that this only works with up to 8 bits. If you want to write longer values, you have to split it up into groups of 8.