FileToBuffer reads a file and creates a new FileBuffer from it.

NewFileBuffer creats a new FileBuffer object.

ErrINV address is invalid.

ErrOOB line is out of bounds.

A Context is passed to an invoked command.

A FileBuffer manages a file being edited.

System is a wrapper around exec.Cmd to run things in the Ed way.

A Command can be run with a Context and returns an error.