I know it's the compose key, and I set it to right Alt and I set the "3rd level" option to the Shift + Alt, but I can't figure out for the life of me for example how to do the copyright symbol, or the registered mark, or trademark symbol, etc. I try alt then c but I get č.
Compose,o,c will produce ©.
You can view the combinations in your locale's Compose file, e.g.
For those without a compose key configured (it isn't by default). Go here for latest versions. On Ubuntu 12.04 the setting is hidden away at System > Preferences > Keyboard > Layout > Options... > Compose Key Position. I prefer to use the "menu" key as compose, but it's a matter of preference.
AltGr (Third-level modifier)
On a UK English layout, AltGr+Shift+c also produces ©.
The standard USA layout doesn't include many characters at the third level as US keyboards have a second Alt rather than AltGr.
The layouts "USA International (AltGr dead keys)" and "USA International" have © at AltGr+c. "USA International (AltGr dead keys)" would be better for most as the other turns the apostrophe into a dead key for the acute accent.
For an occasional unicode character there is always Ctrl+Shift+*unicode-value*
This allows you to type virtually all Unicoode charactesr... (basically all the public ones)
You can get any and all unicode values (Codepoints) from many places;
I find this one the most useful: fileformat.info characcter search
Just search for 'copyright' and take you pick..
The most relevant unicode symbol is
- COPYRIGHT SIGN - U+00A9
To enter it in a Gnome window (like here), just type: Ctrl+Shift+00a9
followed by a space .. use lowercase letters ("a" not "A")
Here are a couple more. Just type Ctrl+Shift where you see U+,
and use lower case letters: a b c d e f
☺ U+263A WHITE SMILING FACE ☻ U+263B BLACK SMILING FACE
Here is a link for general interest (or boredom :)
A count of Unicode characters grouped by script
For searching-and-copying rare chars, this is invaluable:
$ sudo apt-get install unicode
$ unicode copyright U+00A9 COPYRIGHT SIGN UTF-8: c2 a9 UTF-16BE: 00a9 Decimal: © © Category: So (Symbol, Other) Bidi: ON (Other Neutrals) U+2117 SOUND RECORDING COPYRIGHT UTF-8: e2 84 97 UTF-16BE: 2117 Decimal: ℗ ℗ Category: So (Symbol, Other) Bidi: ON (Other Neutrals)
Usually I don't care about the precise unicode properties, the recently added
--terse flag helps. And once it's not so verbose, I don't want the default limit of 10 chars. So I usually call it with:
> unicode --terse --max=0 copyright © U+00A9 COPYRIGHT SIGN ℗ U+2117 SOUND RECORDING COPYRIGHT
For the copyright symbol, try this page . [Actually, do what @misterben says in his terrific answer. I'll leave this link as a curiosity.]
As a generalized answer, if you are typing something odd that you do not often use, do a search for a word containing the character, and cut and paste.
For instance, on the Wikipedia Linguistics page , go to any of the languages listed on the left column. This solution also works for special characters with the correct search.