Question

The awk manual lists this as one of the first examples:

awk "BEGIN { print \"Don't Panic!\" }"

Apparently I should see “Don’t Panic!”, but actually I see:

-bash: !\": event not found

Any ideas?

Answer 1

It all depends on your shell.

> bash
$ awk "BEGIN { print \"Don't Panic!\" }"
bash: !\": event not found
$ tcsh
> awk "BEGIN { print \"Don't Panic!\" }"
Unmatched '.
> sh
$ awk "BEGIN { print \"Don't Panic!\" }"
Don't Panic!
$ 

Exclamation points are used by modern shells to refer to parts of your command line history. In bash and tcsh, they can be interpreted as a history reference. You can escape the ! with a \, or you can leave it out, or you can use a simple shell.

In my bash example above, you see thie failed history substitution. In my tcsh example, you see a problem with quoting (since double quotes can’t be escaped this way). The awk manual you’re using is presumably old enough that it doesn’t assume everyone runs bash.