Convert decimal to hexadecimal in UNIX shell script

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.

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

Hexidecimal to decimal:

$ echo $((0xfee10000))
4276158464

Decimal to hexadecimal:

$ printf '%x\n' 26
1a

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

Try:

printf "%X\n" ${MY_NUMBER}

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.

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
}

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);
    }

SHELL SCRIPTING
LINUX

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).

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