Binary to hexadecimal and decimal in a shell script

Assuming that by binary, you mean binary data as in data with any possible byte value including 0, and not base-2 numbers:

To convert from binary, od (standard), xxd (comes with vim) or perl's unpack come to mind.

od -An -vtu1 # for decimal
od -An -vtx1 # for hexadecimal

xxd -p # for hexa

perl -pe 'BEGIN{$\="\n";$/=\30};$_=unpack("H*",$_)' # like xxd -p

# for decimal:
perl -ne 'BEGIN{$\="\n";$/=\30;$,=" "}; print unpack("C*",$_)'

Now, to convert back to binary, awk (standard), xxd -r or perl's pack:

From the decimal output from od -tu1 or perl above:

awk '{for (i = 1; i <= NF; i++) printf "%c", $i}'
perl -ape '$_=pack("C*",@F)'

From the hexa perl or xxd -p above:

xxd -r -p
perl -pe 'chomp;$_=pack("H*",$_)'

You can use bc for this by manipulating the ibase and obase parameters:

The trick is that you need to be explicit about the bases. So if your ibase is 2, then if you set your obase to 10, it won't do anything, as 10 in binary is 2. Hence you need to use hexadecimal notation.

So binary to decimal would be (watch that obase is A)

Binary to decimal:

$> echo 'ibase=2;obase=A;11110001011010'|bc
15450

Binary to hex:

$> echo 'ibase=2;obase=10000;11110001011010'|bc
3C5A

for binary to hexadecimal use

xxd tool in linux and for binary to decimal you can use qalculate tool.

for help regarding xxd type xxd --help or man xxd in linux.

If you mean converting numbers from base-2 to 10 or 16 and back, bc is the standard tool to do that as already mentioned by psarossy.

decimal=123
binary=$(echo "obase=2;$decimal" | bc)
hex=$(echo "obase=16;ibase=2;$binary" | bc)

Some shells like zsh have builtin support for base conversion as part of their arithmetic expansion operators:

decimal=123
binary=$(([##2]decimal))
hex=$(([##16]decimal))
hex=$(([##16]2#$binary))
decimal=$((2#$binary))

and so on.

Both ksh93 and zsh also support:

typeset -i2 binary=123
typeset -i16 dec2hex=123 bin2hex='2#1111'

But note that, when expanded, $binary will have a 2# or 16# prefix (which you can strip with ${binary#*#}.

ksh93 also supports:

printf "%..2d\n" 123

to convert to binary.