How can I use a --spec file for the jfrog task?

[yogch]

I need to bring a file to the --spec argument.
There's no place to write that file on the jfrog task itself.
It means the spec file is part of the source code, which is fine, or I need to create the spec file in a previous task.

But the spec file should change for each build because it uses different arguments (build number, build name).
Is there a simpler way?

For example, have the spec file stored in git with variables ${bamboo.example} and then pass environment variables in the jfrog task ?