should really be configurable.
S3ZLZP3NXQXP6MOK7ACG7HIEKM66C2DF7PNUZB5LIHSUOOUKGUZQC
CLJQCY2XHIDNNMFBJ5PK3GQEN6RFALEFKXBJRWZPEIKR4PR5ZQ5AC
7YBYT2LQML2PKEO6UO4444AGSASS664UCDXW2YO3ALB7THQHCEBQC
my $cmd = "nix-store --keep-going --no-build-output " .
my $cmd = "nix-store --max-silent-time 1800 --keep-going --no-build-output " .