seq

UNIX下SH的实现源码

# Generate a sequence from m to n, m defaults to 1.

seq ()
{
	declare -i lo hi i	# makes local
	local _SEQ

	case $# in
	1) seq 1 "$1" ; return $? ;;
	2) lo=$1 hi=$2
	   i=$lo _SEQ=""
	   while let "i <= hi"; do
		_SEQ="${_SEQ}$i "
		let i+=1
	   done
	   echo "${_SEQ# }"
	   return 0 ;;
	*) echo seq: usage: seq [low] high 1>&2 ; return 2 ;;
	esac
}

# like the APL `iota' function (or at least how I remember it :-)
iota()
{
	case $# in
	1) seq 1 "$1"; return $?;;
	*) echo "iota: usage: iota high" 1>&2; return 2;;
	esac
}