E: Could not open lock file /var/lib/dpkg/lock-frontend

sudo apt-get update && sudo apt-get -y upgrade; 할때 아래처럼 나오는 경우가 있다

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    E: Could not open lock file /var/lib/dpkg/lock-frontend - open (13: Permission denied)
    E: Unable to acquire the dpkg frontend lock (/var/lib/dpkg/lock-frontend), are you root?

그럴땐 아래처럼 커맨드 치고난 후

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    killall apt apt-get
    sudo rm /var/lib/apt/lists/lock
    sudo rm /var/cache/apt/archives/lock
    sudo rm /var/lib/dpkg/lock*
    sudo dpkg --configure -a

다시 시도해보라

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    sudo apt-get update && sudo apt-get -y upgrade;