# Global Substitution On The Previous Command

Let's say we just executed the following command:

```bash
$ grep 'foo' foo.md
```

It gave us the information we were looking for and now we want to execute
a similar command to find the occurrences of `bar` in `bar.md`. The `^`
trick won't quite work here.

```bash
$ ^foo^bar<tab>
$ grep 'bar' foo.md
```

What we need is a global replace of `foo` in our previous command. The `!!`
command can help when we sprinkle in some `sed`-like syntax.

```bash
$ !!gs/foo/bar<tab>
$ grep 'bar' bar.md
```

For a short command like this, we haven't gained much. However, for large
commands that span the length of the terminal, this can definitely save us
a little trouble.