fillspan

# Highlight a span from a given block of characters
#
# usage: ./fillspan spanofcharacters min max
#
# e.g. ./fillspan 123456789ABCDEF 1 5 =>   [12345          ]
#      ./fillspan 123456789ABCDEF 10 15 => [         ABCDEF]
#      ./fillspan 123456789ABCDEF 5 9 =>   [    56789      ]
bar=$1
min=$2
max=$3
blank=$(echo "$bar" | tr -c ' ' ' ')
premin=$((min-1))
len=$((max-min+1))
postmax=$((max+1))
echo "[${blank:0:$premin}${bar:$premin:$len}${blank:$postmax}]"