Convert decimal to hexadecimal in UNIX shell script - unix

Question

In a UNIX shell script, what can I use to convert decimal numbers into hexadecimal? I thought od would do the trick, but it's not realizing I'm feeding it ASCII representations of numbers.
printf? Gross! Using it for now, but what else is available?

Answer 1

Tried printf(1)?
printf "%x\n" 34
22
There are probably ways of doing that with builtin functions in all shells but it would be less portable. I've not checked the POSIX sh specs to see whether it has such capabilities.

Answer 2

echo "obase=16; 34" | bc
If you want to filter a whole file of integers, one per line:
( echo "obase=16" ; cat file_of_integers ) | bc

Answer 3

Hexidecimal to decimal:
$ echo $((0xfee10000))
4276158464
Decimal to hexadecimal:
$ printf '%x\n' 26
1a

Answer 4

bash-4.2$ printf '%x\n' 4294967295
ffffffff
bash-4.2$ printf -v hex '%x' 4294967295
bash-4.2$ echo $hex
ffffffff

Answer 5

Sorry my fault, try this...
#!/bin/bash
:
declare -r HEX_DIGITS="0123456789ABCDEF"
dec_value=$1
hex_value=""
until [ $dec_value == 0 ]; do
rem_value=$((dec_value % 16))
dec_value=$((dec_value / 16))
hex_digit=${HEX_DIGITS:$rem_value:1}
hex_value="${hex_digit}${hex_value}"
done
echo -e "${hex_value}"
Example:
$ ./dtoh 1024
400

Answer 6

Try:
printf "%X\n" ${MY_NUMBER}

Answer 7

In my case, I stumbled upon one issue with using printf solution:
$ printf "%x" 008
bash: printf: 008: invalid octal number
The easiest way was to use solution with bc, suggested in post higher:
$ bc <<< "obase=16; 008"
8

Answer 8

In zsh you can do this sort of thing:
% typeset -i 16 y
% print $(( [#8] x = 32, y = 32 ))
8#40
% print $x $y
8#40 16#20
% setopt c_bases
% print $y
0x20
Example taken from zsh docs page about Arithmetic Evaluation.
I believe Bash has similar capabilities.

Answer 9

xd() {
printf "hex> "
while read i
do
printf "dec $(( 0x${i} ))\n\nhex> "
done
}
dx() {
printf "dec> "
while read i
do
printf 'hex %x\n\ndec> ' $i
done
}

Answer 10

# number conversion.
while `test $ans='y'`
do
echo "Menu"
echo "1.Decimal to Hexadecimal"
echo "2.Decimal to Octal"
echo "3.Hexadecimal to Binary"
echo "4.Octal to Binary"
echo "5.Hexadecimal to Octal"
echo "6.Octal to Hexadecimal"
echo "7.Exit"
read choice
case $choice in
1) echo "Enter the decimal no."
read n
hex=`echo "ibase=10;obase=16;$n"|bc`
echo "The hexadecimal no. is $hex"
;;
2) echo "Enter the decimal no."
read n
oct=`echo "ibase=10;obase=8;$n"|bc`
echo "The octal no. is $oct"
;;
3) echo "Enter the hexadecimal no."
read n
binary=`echo "ibase=16;obase=2;$n"|bc`
echo "The binary no. is $binary"
;;
4) echo "Enter the octal no."
read n
binary=`echo "ibase=8;obase=2;$n"|bc`
echo "The binary no. is $binary"
;;
5) echo "Enter the hexadecimal no."
read n
oct=`echo "ibase=16;obase=8;$n"|bc`
echo "The octal no. is $oct"
;;
6) echo "Enter the octal no."
read n
hex=`echo "ibase=8;obase=16;$n"|bc`
echo "The hexadecimal no. is $hex"
;;
7) exit
;;
*) echo "invalid no."
;;
esac
done

Answer 11

This is not a shell script, but it is the cli tool I'm using to convert numbers among bin/oct/dec/hex:
#!/usr/bin/perl
if (#ARGV < 2) {
printf("Convert numbers among bin/oct/dec/hex\n");
printf("\nUsage: base b/o/d/x num num2 ... \n");
exit;
}
for ($i=1; $i<#ARGV; $i++) {
if ($ARGV[0] eq "b") {
$num = oct("0b$ARGV[$i]");
} elsif ($ARGV[0] eq "o") {
$num = oct($ARGV[$i]);
} elsif ($ARGV[0] eq "d") {
$num = $ARGV[$i];
} elsif ($ARGV[0] eq "h") {
$num = hex($ARGV[$i]);
} else {
printf("Usage: base b/o/d/x num num2 ... \n");
exit;
}
printf("0x%x = 0d%d = 0%o = 0b%b\n", $num, $num, $num, $num);
}

Answer 12

For those who would like to use variables, first export it by running:
export NUM=100
Then run:
printf "%x\n" $NUM
Else, you can you can ignore the use case of the variables and run it directly as shown below:
printf "%x\n" 100
NB:Substitute NUM with the variable name of your choice.
Exporting makes it an environmental variable(global).

Answer 13

Wow, I didn't realize that printf was available at the shell!
With that said, I'm surprised no-one commented about putting the printf into a shell script (which then you could put in your personal bin directory if you wanted).
echo "printf "0x%x\n" $1" > hex
chmod +x hex
Now just run:
./hex 123
It returns:
0x7b