tmpf=$TMPDIR/tmp-$$
printf "%s\n" "one two three four" > $tmpf

# make sure we rewind the input properly when reading a specific number of
# characters or using a non-standard delimiter from a regular file

exec <$tmpf
read -n 4 input && echo "$input"
cat -

exec <$tmpf
read -d ' ' input && echo "$input"
cat -

rm -f $tmpf