Command line editing is a function of your shell, not of Terminal. Probably your shell is bash and probably its command line editing style is set to “emacs”.
Here are a few of the Emacs-style key combinations that you might find handy:
kill-word (delete the next ‘word’)
C-x means Control+x, so C-a is Control+a.
M-x means Meta+x, but there probably is no Meta key on your keyboard. So instead, you can use ESC x (i.e. Escape then x). Terminal has an setting to automatically send ESC before keys pressed with Option held down. Using this feature disables the extended character handling that Mac OS X usually provides when using the Option modifier. So, if you use few extended characters and want to have Option+x send ESC x, then you can enable this Terminal option.
There are lots of ways of moving to “Hello” in your example:
- Search for “Hello”: C-r H e l l o C-j (or ESC)
- In normal Emacs, you would just use RET (Return) to end the search at the current location and return to editing. But in bash, the default bindings cause RET (i.e. C-m) to always execute the current line, even if an incremental search is active. So the C-j/ESC part is a deviation from normal Emacs.
- Jump to the beginning of the line and move forward: C-a M-f C-f (or →)
- Jump to the beginning of the line, then move by words: C-a M-f M-f M-b
- Use M-b a lot (only really feasible if you map Option to Meta).
There are also several ways of accomplishing your desired replacement:
- delete the word and replace it: M-d H i
- delete characters and replace them: C-d C-d C-d C-d C-d H i
- move past “H” and delete the following work, replace it: C-f M-d i
- move past “H” and delete the remaining characters, replace them: C-f C-d C-d C-d C-d i
If you stopped at the end of the word (maybe via C-a M-f M-f), you could use M-DEL H i.
You might do something like
bind -P | less to find other interesting bindings. Consult the readline section of the bash man page (or the readline parts of the bash info pages) for details.