This removes the conditions that checks if the password is supplied
through environment variable or file and outputs password is successful
on terminal and when --quiet is not supplied.
This adds some feedback when entering the password on the command line.
When the password is entered and supplied through stdin (and stdout is a
terminal) then the a message saying `password is correct` if correct is
printed.
This commits adds rudimentary support for a cache directory, enabled by
default. The cache directory is created if it does not exist. The cache
is used if there's anything in it, newly created snapshot and index
files are written to the cache automatically.
This was a bit tricky: We start the ssh binary, but we want it to ignore
SIGINT. In contrast, restic itself should process SIGINT and clean up
properly. Before, we used `setsid()` to give the ssh process its own
process group, but that means it cannot prompt the user for a password
because the tty is gone.
So, now we're passing in two functions that ignore SIGINT just before
the ssh process is started and re-install it after start.
Instead of determining the password lazily during ReadPassword(), do so now in
cobra.PersistentPreRunE() so we can store the result in the globalOptions and
reuse/override when applicable without having to worry about the environment
or flag options interfering.
The method of determining if a repository exists doesn't work on Windows, since
the "url.Scheme" will contain the drive letter - "c" in "c:\backup",
so as a first step we check if the URL can be opened as a file,
and if so, we assume it is a 'local' type repository.
