How to modify environment variables before executing a command

[Malte Forkel]

Peter Stuge schrieb:
> Malte Forkel wrote:
>> Any more suggestions on how to modify environment variables before
>> executing a command via ssh?
> 
> You can use SendEnv in the client configuration. But the server must
> also AcceptEnv those same variables.

The command I execute via ssh installs packages into a repository on the
server. The environment variable I'd like to be able to modify is used
to access an instance of gpg-agent on the server. So unfortenately,
SendEnv does not help me in this case because the value of the
environment variable is known/created on the server.

Malte