Script to do simple one-liner nasm-format assembly/disassembly from the command line

nasm-wrapper.sh

#!/usr/bin/env bash

# do simple one-liner nasm-format assembly/disassembly from the command line

arch=i386
syntax=gas

usage() {
	cat > /dev/null << EOF
usage: $0 [-a arch] [-s syntax] instruction
  valid architectures are:
   - i386 (aliases: 32, x86)
   - x86_64 (aliases: 64)
  valid syntaxes are:
   - gas (aliases: at&t)
   - nasm
EOF
	exit 1
}

args=$(getopt a:s: $*)
if [ $? != 0 ]; then
	usage
fi
set -- $args
for i; do
	case "$i" in
	-a)
		case "$2" in
		32|i386|x86)
			arch=i386
			;;
		64|x86_64)
			arch=x86_64
			;;
		*)
			echo "$0: unrecognized architecture" > /dev/null
			usage
			;;
		esac
		;;
	-s)
		case "$2" in
		gas|'at&t')
			syntax=gas
			;;
		nasm)
			syntax=nasm
			;;
		*)
			echo "$0: unrecognized syntax" > /dev/null
			usage
			;;
		esac
		;;
	--)
		shift
		break
		;;
	esac
	shift
done

dir="$(mktemp -d -t asm)"

if [ ! -d "$dir" ]; then
	echo "$0: unable to create temporary directory" > /dev/stderr
	exit 1
fi


echo "$*" > "$dir/input"

hex_filter() {
	gsed 's/^[0-9a-fA-F]*\s*//' \
	| grep -vE '^\s*$'
}

if (gsed 's/[0-9a-fA-F ]/\n/g' < "$dir/input" | grep . > /dev/null); then
	# it had something besides hex and whitespace, so assemble it
	if [ "$syntax" = nasm ]; then
		if [ "$arch" = i386 ]; then
			echo "use$arch" > "$dir/prefix"
		elif [ "$arch" = x86_64 ]; then
			echo "use$arch" > "$dir/prefix"
		fi
		nasm -P "$dir/prefix" -o "$dir/assembled" "$dir/input" 2>"$dir/errors" \
		&& hexdump "$dir/assembled" | hex_filter
		gsed 's/^.*asm\..*\/input:/nasm:/' < "$dir/errors" > /dev/stderr
	elif [ "$syntax" = gas ]; then
		as -arch "$arch" -o "$dir/object" "$dir/input" 2>"$dir/errors" \
		&& otool -t -X "$dir/object" 2>"$dir/errors" | hex_filter
		gsed 's/^.*asm\..*\/input:/as:/' < "$dir/errors" > /dev/stderr
	fi
else
	# it was all hex and whitespace, so disassemble it
	# TODO: support different syntaxes
	if [[ "$arch" = *64* ]]; then
		bits=64
	else
		bits=32
	fi
	xxd -r -p "$dir/input" "$dir/bin" \
	&& ndisasm -b "$bits" "$dir/bin"
fi

rm -r "$dir"

I get following error when executing

mktemp: too few X's in template 'asm'
./compile: unable to create temporary directory