Add more examples using associate array variables

sheets/awk

@@ -27,3 +27,11 @@ free | awk '{i++} END{print i}'
 
 # Output a (unique) list of available sections under which to create a DEB package.
 awk '!A[$1]++{print($1)}' <<< "$(dpkg-query --show -f='${Section}\n')"
+
+# Using process substitution (`<()` is NOT command substitution), with AWK and its
+# associative array variables, we can print just column 2 for lines whose first
+# column is equal to what's between the double-quotes.
+awk '{NR!=1&&A[$1]=$2} END{print(A["Mem:"])}' <(free -h)
+# While below is an easier and simpler solution to the above, it's not at all the
+# same, and in other cases, the above is definitely preferable; more accurate.
+awk '/^Mem:/{print($2)}' <(free -h)