Can usage of free software be restricted?

[Jonas Jørgensen]

Eric Feliksik wrote:
> Because I'm in doubt about the necessity of the instruction to read and 
> accept the licenses. What free-software licenses do you have to agree on 
> in order to use the software the license covers? AFAIK at least the GPL 
> does not restrict usage in any way; this means the GPL has to be 
> accepted *only* if someone wants to redistribute the software. If the 
> GPL is not accepted, there is no permission to redistribute the 
> copyrighted work. When installing firefox the license has to be agreed 
> on, but does the Mozilla-tri-license require that?

Specifically with Firefox, you should be safe. Since the tri-license 
means that you can use it under the terms of the GPL, Firefox can safely 
be used without reading the license, as any other GPL'ed program.

I don't have an answer about any other license.

Regards,
Jonas