string from $string at $position.
If the $string parameter is "*" or "@", then this extracts the positional parameters, [1] starting at $position.
<code>${string:po... # Three characters of substring.
If the $string parameter is "*" or "@", then this extracts a maximum of $length positional parameters, starting at $position.
<code>
echo ${*:2} ... o bar baz; do eval echo \${$foo:?} one bash: bar: parameter null or not set bash: baz: parameter null or not set
== NOTE ==
The colon (:) in t... pt. Omitting message produces the default message parameter null or not set.
Purpose:
Catching errors tha
