Error when following instructions "Install firefox on ChromeOS"

Resolved Update: apparently cat cannot write to /etc. Resolved by using: sudo tee /etc/apt/sources.list.d/mozilla.sources <<EOF Types: deb URIs: https://packages.mozilla.org/apt Suites: mozilla Components: main Signed-By: /etc/apt/keyrings/packages.mozilla.org.asc EOF The instructions need updating! _________________original problem (in case some one else needs the information) I am following the instructions in section "Install Firefox from Mozilla Repository (Recommended)" at https://support.mozilla.org/en-US/kb/run-firefox-chromeos At step 4 I am receiving a permission denied error: "-bash: /etc/apt/sources.list.d/mozilla.sources: Permission denied" I am not sure how to resolve or continue. Last command and output: username@penguin:~ cat <<EOF > /etc/apt/sources.list.d/mozilla.sources Types: deb URIs: https://packages.mozilla.org/apt Suites: mozilla Components: main Signed-By: /etc/apt/keyrings/packages.mozilla.org.asc EOF -bash: /etc/apt/sources.list.d/mozilla.sources: Permission denied