"Rather than stand for that, just do the following
thing whenever you log into your shell. Always make sure that you
have line editing enabled. In bash, ksh, etc, if you want to enable
vi line editing, all you need to do is type:
"host # set -o vi
"on the command line or, better yet, at it to your
.bash_profile, .profile or .bashrc, so line editing will get set
every time you log in and you won't have to always remember to do
it. If you like emacs, just replace vi in the example above. This
way, once you get to the end of that long line, you can type
(literally)
"[esc]0i#[enter]
"That's the escape key (to get into vi command mode), the number
0 (to whisk you back to the beginning of the line), the letter i
(to get you out of vi command mode and into insert mode) and the
pound (#) symbol (to make the whole line a comment) and then the
enter key. This will cause your line to become a comment, just like
in a shell script and the shell won't execute it. Then you can type
your preceding line and (assuming vi again) type: