joining contents in line with strings

joinline.sh

#!/usr/bin/env bash
#
# MIT license
# Author: EKEYME@GMAIL.COM
#
# joining contents in line with strings

short_usage="$(basename $0) [-h] [join_string] [left-closer [right-closer]]"
# display usage
usage() {
    cat <<EOF
usage: $short_usage
Joining contents in line with strings from <stdin>.

  -h, --help                      show this help message and exit
  join_string                     join string, used to replace the new line
  closer                          closer string, used to close the whole joined string
EOF
}

if [[ $1 == -h || $1 == --help ]]; then
	usage
	exit
fi
if (($# > 3)); then
	echo "usage: $short_usage" >&2
	echo "$(basename $0): error: arguments should no more than 3" >&2
	exit 1
fi

if (($# == 0)); then
	join_string="','"
	lcloser="'"
	rcloser="'"
elif (($# == 1)); then
	join_string=$1
	lcloser=""
	rcloser=""
elif (($# == 2)); then
	join_string=$1
	lcloser=$2
	rcloser=$2
else
	join_string=$1
	lcloser=$2
	rcloser=$3
fi

exec 3< <(tac | tac)

read -u3 line
if (($? == 1)); then
	exit
fi

printf "%s" "$lcloser"
while true; do
	read -u3 current_line
	if (($? == 1)); then
		printf "%s%s" "$line" "$rcloser"
		break
	else
		line=${line%$'\r'}
		printf "%s%s" "$line" "$join_string"
	fi
	line=$current_line
done
echo

exec 3<&-