padding_examples.sh

#
# Christian Kujau <lists@nerdbynature.de>
#
# Zero-padding examples in Bourne shell
# Based on some wonderful examples from
# http://jonathanwagner.net/2007/04/zero-padding-in-bash
#

if [ -z "$2" ]; then
	echo "Usage: `basename $0` (`awk '/^\t[a-z0-9]*\)$/' "$0" | xargs echo | sed 's/) /|/g'` [count]"
	exit 1
else
	 MODE="$1"
	COUNT="$2"
fi

# How long to pad for?
w=${#COUNT}			# expr length $COUNT
					# echo $COUNT | awk '{print length}'

case $MODE in
	bash4)
	# Bash-4.0 needed for zero-padding with braces
	# see http://tldp.org/LDP/abs/html/bashver4.html#BRACEEXPREF4
	if [ "${BASH_VERSINFO[0]}" -lt 4 ]; then
		echo "Bash-4.0 needed!"
		exit 1
	fi

	# For some reason this is not working in non-interactive shells
	w=`expr $w + 1`
	echo {01..$COUNT} | fold -"$w"
	;;

	bash41)
	# Bash-4.1 needed for "printf -v"
	# see http://tldp.org/LDP/abs/html/bashver4.html#AEN21051
	if [ "${BASH_VERSINFO[0]}" -lt 4 -o "${BASH_VERSINFO[1]}" -lt 1 ]; then
		f=`printf "%"$w"s"`
		p=`printf "%s\n" "${f// /0}"`
	else
		p=`printf -v f "%"$w"s"; printf "%s\n" "${f// /0}"`
	fi

	x=1
	while [ $x -le $COUNT ]; do
		echo ${p:${#x}}$x
		x=$((x+1))
	done
	;;

	printf)
	x=1
	while [ $x -le $COUNT ]; do
		printf "%0"$w"d\n" $x
		x=$((x+1))
	done
	;;

	seq)
	# Maybe seq(1) is installed as GNU seq?
	 seq --help > /dev/null 2>&1 && SEQ=seq
	gseq --help > /dev/null 2>&1 && SEQ=gseq
	$SEQ -w 1 $COUNT 2>/dev/null || echo "seq(1) from coreutils needed!"
	;;
	
	*)
	echo "hm?"
	;;
esac