How to cycle through reverse-i-search in BASH?

If I understand the question correctly you should be able to cycle through alternatives by repeatedly hitting Ctrl+R.

E.g.:

Ctrl+R grep Ctrl+R Ctrl+R ...

That searches backwards through your history. To search forward instead, use Ctrl+S, but you may need to have set: stty -ixon (either by .bash_profile or manually) prior to that to disable the XON/XOFF feature which takes over Ctrl+s. (More details here.)

If you feel the command will be used frequently, you could add a tag

command #useful

Then

ctrl+r #useful

This works because # is a comment delimiter, i.e. everything that comes after the symbol is not interpreted as a command. However, it will be recorded in the history and is thus searchable.

You can also set up the up and down arrows to do a slightly different search by adding these lines to ~/.inputrc:

"\e[A": history-search-backward
"\e[B": history-search-forward

Instead of searching for a substring anywhere in the command (like Ctrl-r) it will search for a command starting with the text to the left of the cursor. For example, if I run these commands:

$ ls bart
$ ls fools

then type ls and press Up twice, it will show ls bart and the cursor in the same place. Compare with Ctrl-r, where it would find the ls twice in the last line, so you'd have to press it once again to find the previous line.

These approaches both have their strengths, and both of them can save a lot of time.