String concatenation operators

These operators concatenate strings. The syntax is:

<target> .= <right_operand>
<target> << <right_operand>
<target> <, <right_operand>

Operator .= appends <right_operand> to <target>. Operator << appends a space followed by <right_operand> to <target> if <target> is non empty, otherwise sets <target> to <right_operand>. Operator <, is similar to << but uses a comma to separate the two variable contents. The last two operators are useful in creating space-separated or comma-separated lists.

Examples

%a = ""
%a << free
echo %a
%a .= bsd
echo %a
%a << rox
echo %a
%a <, but linux is better!
echo %a