Have to use ksh. No lesser sh has arrays.
#!/usr/bin/ksh

exec 5<file.txt
set -A array
i=0
while read -ru5 array[$i]; do
i=$(($i+1))
done

# And, to be complete
i=0
j=${#array[@]}
while [ $i -lt $j ]; do
echo ${array[$i]}
i=$(($i+1))
done
_________________________
Bitt Faulk