BASH history manipulation: search replace

Question

There is a really handy parameter/variable expansion feature in BASH that I don't see for history. I've checked man pages for history and for BASH itself. Not there ...maybe I missed it.

Example: I use ssh a lot and I can do this with variable expansion.

host=foo@bar.org

Suppose I wanted to extract just the host -- rather, remove the username.

hostonly=${host##*@}

If I

echo $hostonly

I get:

bar.org

My question: Is it possible to do this with commandline history?

eg.,

Command 1:

ssh foo@bar.org

Command 2:

ssh gary@!!:##*@

This doesn't work, of course, but can someone confirm whether or not this type of pattern matching is available?

Thanks!

Bubnoff

Answer 1

A neat trick often missed by people is the r command (which is itself a special case of the fc command):

$ ssh foo@bar.org
(...)
$ r foo=baz

The more general case is

$ fc -s foo=bar ssh

which lets you select a command from the history by substring, then perform the specified substitution and run it. If you leave off the -s, it will load the command into $EDITOR for more complex modification; command line editing mostly makes this unnecessary, but there are some edits that are hard to do on the command line.

You can also do fairly complex manipulation using ! history reference syntax, but for historical reasons (the basic history mechanism was established by early csh and all enhancements have mostly kept compatibility) it uses a different syntax. See here for details.

Answer 2

$ ssh foo@bar.org
...
$ ^foo^gary^
...

The command is repeated using "gary" as the username instead of "foo". The following works the same way:

$ ssh foo@bar.org
...
$ !!:s/foo/gary/
...