Shell Programming and Scripting

N=0
ARR=()
# Special variable which controls when unquoted variables split.
# By default it's space, but we want to split on , for the csv
IFS=","

# Read the entire file one line at a time, putting each line in STR
while read STR
do
...
done <file.csv

# set -- a b c will set $1="a", $2="b", $3="c"
# If we set IFS=",", and VAR="a,b,c", then do set -- $VAR, it will
# set $1="a", $2="b", $3="c"
# So we use it here to split a line of "a,b,c" into $1, $2, $3.
set -- $STR

# $# is a special variable defining how many $1 variables we have.
# If we have $1, $2, $3, $# will be 3.  We loop until they're all gone.
while [ $# -gt 0 ]
do
        ARR[$N]=$1 # Put it in the array at index N
        ((N++)) # Increment N
        shift # Remove $1, set $1=$2, $2=$1, ...
done