Does it mean default answer as yes reg any questions that may pop up? If so, why not use "-y"?
The -yq, surpress output normally spit out by the command and the -y forces a yes answer to all the questions that the package manager would ask, like "Should the package xxx be installed (Y/n)? ".
Quiet; produces output suitable for logging, omitting progress indicators. More q’s
will produce more quiet up to a maximum of 2. You can also use -q=# to set the quiet
level, overriding the configuration file. Note that quiet level 2 implies -y; you
should never use -qq without a no-action modifier such as -d, –print-uris or -s as
APT may decide to do something you did not expect. Configuration Item: quiet.
-y, –yes, –assume-yes
Automatic yes to prompts; assume "yes" as answer to all prompts and run
non-interactively. If an undesirable situation, such as changing a held package,
trying to install a unauthenticated package or removing an essential package occurs
then apt-get will abort. Configuration Item: APT::Get::Assume-Yes.