この記事は次のようなエラーについての話です

myuser@ubuntu:~$ sudo apt update && sudo apt upgrade -y
Reading package lists... Done
E: Could not get lock /var/lib/apt/lists/lock. It is held by process 1519 (apt-get)
N: Be aware that removing the lock file is not a solution and may break your system.
E: Unable to lock directory /var/lib/apt/lists/

とか

myuser@ubuntu:~$ sudo apt update && sudo apt upgrade -y
Hit:1 http://ports.ubuntu.com/ubuntu-ports jammy InRelease
Hit:2 http://ports.ubuntu.com/ubuntu-ports jammy-updates InRelease
Hit:3 http://ports.ubuntu.com/ubuntu-ports jammy-backports InRelease
Hit:4 http://ports.ubuntu.com/ubuntu-ports jammy-security InRelease
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
34 packages can be upgraded. Run 'apt list --upgradable' to see them.
Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 1863 (apt-get)
Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 1863 (apt-get)
^Citing for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 1863 (apt-get)... 2s

みたいなエラーを見かける時があります。

こんな時、Could not get lockの部分だけGoogleで調べたりすると「lockやlock-frontendを削除すれば直る」という情報と出会うことになります。

しかし、注目すべきはその箇所ではなく・・・

Could not get lock /var/lib/apt/lists/lock. It is held by process 1519 (apt-get)

Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend. It is held by process 1863 (apt-get)

の

It is held by process 1519 (apt-get) の部分です！

数字はPID(プロセスID)です。psコマンドにこのIDを渡すことでプロセスの正体を明らかにすることができます。

プロセスを調べてみよう

myuser@ubuntu:~$ ps 1863
    PID TTY      STAT   TIME COMMAND
   1863 ?        S      0:06 /usr/bin/apt-get --option=Dpkg::Options::=--force-confold --option=Dpkg::options::=--force-unsafe-io --assume-yes --quiet install avahi-daemon

何かのインストールをしているようです。しばらく待てば終わりそうなので数分待ってからもう一度psコマンドを実行してみると・・・

myuser@ubuntu:~$ ps 1863
    PID TTY      STAT   TIME COMMAND

無事に処理が終了したみたいですね😊

最初に失敗した`apt`コマンドを再実行してみよう

myuser@ubuntu:~$ sudo apt upgrade -y
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following NEW packages will be installed:
  linux-headers-5.15.0-1063-raspi linux-image-5.15.0-1063-raspi linux-modules-5.15.0-1063-raspi linux-raspi-headers-5.15.0-1063
The following packages will be upgraded:
  apparmor ca-certificates cloud-init curl libapparmor1 libcurl3-gnutls libcurl4 libexpat1 libmm-glib0 libpcap0.8 libpython3.10 libpython3.10-minimal libpython3.10-stdlib linux-firmware linux-headers-raspi
  linux-image-raspi linux-raspi python3-configobj python3-pkg-resources python3-setuptools python3.10 python3.10-minimal ubuntu-advantage-tools ubuntu-minimal ubuntu-pro-client ubuntu-pro-client-l10n
  ubuntu-server ubuntu-server-raspi ubuntu-standard vim vim-common vim-runtime vim-tiny xxd
34 upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
21 standard LTS security updates
Need to get 392 MB of archives.
After this operation, 339 MB of additional disk space will be used.
Get:1 http://ports.ubuntu.com/ubuntu-ports jammy-updates/main arm64 libexpat1 arm64 2.4.7-1ubuntu0.4 [77.4 kB]
...

今度は問題なく動きました！

まとめ

lockファイル関連のエラーが出ても、焦らずエラーメッセージを読んで適切に対処していきましょう😊

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