On page 32 on shell conditions the authors suggest that the trailing ] is also added just for readability. This is wrong and an opening '[' must be followed by a closing one ']'. Following the discussion, a weird example is added:
ls -l /usr/bin [
which makes no sense at all and just produces an error message that the file '[' was not found!

this is not wrong. you have an extra space in your command. try it with no space between the slash and bracket:

--- cut ---
# ls -l /usr/bin/[
-rwxr-xr-x 1 root root 22132 Aug 6 23:36 /usr/bin/[
--- cut ---

Aminm:

The command "ls -l /usr/bin/[" is not an example at all of using the open bracket. The author is just proving that the close bracket is not needed by showing that the '[' is merely a symlink to the test command.

Murdock