*Convert Binary,HEX, Oct to decimal*
This is a small Shell tutorial on how to convert different bases to other bases.

Some times when working as system admin you require to convert different number systems to others. In this post we will see how to convert different number systems to others.

**Decimal to Binary**
echo "obase=2; 23" | bc

**Output:**

10111
Let me explain above command. obase is a special variable in bc command which defines the output base value for a given number. There is one more special variable for bc command called ibase which defines input base value. In our example we did not mention ibase so by default it will take my input value as decimal value. So we feed obase=2 and decimal number 23 to bc command to convert decimal 23 in to binary number.

**Decimal to Octal number**
echo "obase=8; 23" | bc

Decimal to Hex number
echo "obase=16; 23" | bc

**Decimal to any base number**

convert decimal number to base 4 number system
echo "obase=4; 23" | bc

**How about convert to base 7?**
echo "obase=7; 23" | bc

**Binary to decimal**
echo "ibase=2; 11010101" | bc

**Oct to decimal**
echo "ibase=8; 723" | bc

**Hex to decimal**
echo "ibase=16; 23" | bc

How about converting binary to Oct?
echo "ibase=2;obase=8 1010101" | bc

As given above we can convert any number system to any number systems

Other ways to do base convertions

bc will convert from any base to any other base. There are some other tools which can do partially these conventions.

$(()) –can convert hex to decimal

example:

echo $((0x123))

printf command can convert hex and oct to decimal

**decimal to Octal**
printf "%o\n" 123

**decimal to Hex**
printf "%x\n" 123