erator (${#array[*]}) has to do with array variables.
==== String Length ====
<code>
${#string}
... string of first character in $substring that matches.
<code>
stringZ=abcABC123ABCabc
echo `expr index... 1c` # 3
# 'c' (in #3 position) matches before '1'.</code>
This is the near equivalent of strchr() in C.
==== Substr ====
Shell uses zero-based indexing. When substring expansion of
ode>
----
<
is less than (within double parentheses)
<code>(("$a" < "$b"))</code>
----
//<=//
is less than or equal to (within double parentheses)
<code>(("$a" <= "$b"))</code>
----
>
is greater than (within double parentheses)
<code>(("$a" > "$b"))</code>
----
//>=//
is greater than or equal to (within double parentheses)
<code>(("$a" >= "$b"))</code>
==== string comp
