Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend 해결 방법

문제

다음과 같이 Waiting for cache lock 에러가 발생하고 업데이트가 정상적으로 진행이 안되는 문제가 발생했다.

root@taking:~/ # apt install unrar -y
Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 15973 (unattended-upgr)... 11s
^Citing for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 15973 (unattended-upgr)... 19s
에러 발생

해결방법

apt 내 lock 파일이 존재하기 때문에 발생한다. 다른 세션에서 apt를 점유하고 있는 경우가 아니라면 lock 파일을 제거해주어 문제를 해결하면 된다.

# lock 파일 제거
rm /var/lib/apt/lists/lock 
rm /var/cache/apt/archives/lock
rm /var/lib/dpkg/lock*

# 패키지 업데이트
dpkg --configure -a
apt update
Lock 파일 제거

해결 후

lock 파일 제거 후, 다시 apt update 및 패키지 인스톨을 진행하면 다음과 같이 정상적으로 설치가 진행되는 것을 볼 수 있다.

root@taking:~/# apt install unrar -y
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  unrar
0 upgraded, 1 newly installed, 0 to remove and 78 not upgraded.
Need to get 113 kB of archives.
After this operation, 406 kB of additional disk space will be used.
Get:1 http://nova.clouds.archive.ubuntu.com/ubuntu focal/multiverse amd64 unrar amd64 1:5.6.6-2build1 [113 kB]
Fetched 113 kB in 1s (78.7 kB/s)
Selecting previously unselected package unrar.
(Reading database ... 147886 files and directories currently installed.)
Preparing to unpack .../unrar_1%3a5.6.6-2build1_amd64.deb ...
Unpacking unrar (1:5.6.6-2build1) ...
Setting up unrar (1:5.6.6-2build1) ...
update-alternatives: using /usr/bin/unrar-nonfree to provide /usr/bin/unrar (unrar) in auto mode
Processing triggers for man-db (2.9.1-1) ...
문제 해결 후 패키지 업데이트 진행
You've successfully subscribed to taking
Great! Next, complete checkout to get full access to all premium content.
Error! Could not sign up. invalid link.
Welcome back! You've successfully signed in.
Error! Could not sign in. Please try again.
Success! Your account is fully activated, you now have access to all content.
Error! Stripe checkout failed.
Success! Your billing info is updated.
Error! Billing info update failed.