A simple replacement for command `tree` for use when you can't install tree

tree.sh

#! /bin/sh
#
# tree.sh
# 
#


declare max_level=10
declare dir="$1"
declare -r last="└-"
if [ -z "$dir" ]; then
    dir="$(pwd)"
fi

function show_dir()
{
    local ident="$2"
    local basedir="$1"
    local level="$(($3+1))"
    if [ $level -gt $max_level ]; then
        echo
    else
        list="$(ls $1)"
        index=1
        size=$(echo $list | wc -w )
        for i in $(echo $list)
        do
            if [ -d "${basedir}/$i" ]; then
                if [ $index == $size ]; then
                    echo "$ident $last $i"
                    show_dir "${basedir}/$i" "$ident   "
                else
                    echo "$ident ├- $i"
                    show_dir "${basedir}/$i" "$ident | "
                fi
            else
                if [ $index == $size ]; then
                    echo "$ident $last $i"
                else
                    echo "$ident ├- $i"
                fi
            fi
            index=$(($index+1))

        done
    fi

}

show_dir $dir "| " 1