Simple shell scripts to convert decimal to hex in bash (and visa versa) with various formatting options

dec_to_hex

#!/bin/bash -ue
##
# Simple shell script to convert decimal to hex
# Created by hongkongkiwi: https://gist.github.com/hongkongkiwi/02d8bcde0c810f8dff6b6a96d11ce6bd
# Usage:
# ./dec_hex "12356"
# ./dec_hex -n "12356"
# ./dec_hex -n -l "12356"
# ./dec_hex -n -l -o "12356"
##
HELP="$0 [-n|--no-leading] [-o|--hex-only] [-l|--lowercase] <integer>"
NO_LEADING=""
HEX_ONLY=""
LOWERCASE=""
for ARG in $@; do
  case "$ARG" in
    '-n'|'--no-leading') NO_LEADING="yes";;
    '-o'|'--hex-only') HEX_ONLY="yes";;
    '-l'|'--lowercase') LOWERCASE="yes";;
    '-h'|'--help') echo >&2 "$HELP"; exit 255;;
  esac
  # Number is always last arg
  NUM="$ARG"
done
if ! [[ "$NUM" =~ ^[0-9]+$ ]]; then
  echo >&2 "ERROR: pass a decimal integer"; echo >&2 "$HELP"; exit 255;
fi
if [ -n "$NO_LEADING" ]; then
  # Strip off leading zeros as printf does not like it
  NUM="$(echo "$NUM" | sed 's|^[0]*||g')"
  OUTPUT="$(printf "%x\n" "$NUM")"
else
  # Strip everything but leading zeros
  LEADING="$(echo "$NUM" | sed -n 's/^\([0]*\)[0-9]\+/\1/p')"
  # Strip off leading zeros as printf does not like it
  NUM="$(echo "$NUM" | sed 's|^[0]*||g')"
  OUTPUT="$(printf "${LEADING}%x\n" "$NUM")"
fi
if [ -n "$LOWERCASE" ]; then
  OUTPUT="$(echo "$OUTPUT" | tr '[:upper:]' '[:lower:]')"
else
  OUTPUT="$(echo "$OUTPUT" | tr '[:lower:]' '[:upper:]')"
fi
if [ -n "$HEX_ONLY" ]; then
  echo "$OUTPUT"
else
  echo "0x$OUTPUT"
fi
exit 0

hex_add

#!/bin/bash -ue
command -v "dc" >/dev/null 2>&1 || { echo >&2 "I require dc but it's not installed.  Aborting."; exit 1; }
TOTAL_HEX="00000"
for HEX_NUM in $@; do
  TOTAL_HEX="$(echo "$TOTAL_HEX" "${HEX_NUM#"0x"}" | dc -e '16o16i?+p')"
done
echo "0x$TOTAL_HEX"

hex_to_dec

#!/bin/bash -ue
[ -n "${1-}" ] || { echo >&2 "ERROR: pass a hex number"; exit 255; }
printf "%d\n" "0x${1#"0x"}"