【Linux】ユーザにsudo権限を付与・削除する方法

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$ id test-user
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uid=1001(test-user) gid=1001(test-user) groups=1001(test-user)
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$ cat /etc/passwd | grep test-user
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test-user:x:1001:1001:,,,:/home/test-user:/bin/bash

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$ groups test-user
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test-user : test-user
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$ cat /etc/group | grep test-user
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test-user:x:1001:

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$ sudo apt update
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[sudo] password for test-user:
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test-user is not in the sudoers file.  This incident will be reported.

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～
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# User privilege specification
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root    ALL=(ALL:ALL) ALL
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# Members of the admin group may gain root privileges
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%admin ALL=(ALL) ALL
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# Allow members of group sudo to execute any command
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%sudo   ALL=(ALL:ALL) ALL
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～

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$ cat /etc/group | grep sudo
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sudo:x:27:userX

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sudo usermod -aG sudo test-user

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$ groups test-user
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test-user : test-user sudo
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$ cat /etc/group | grep sudo
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sudo:x:27:userX,test-user

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$ su - test-user
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Password:
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To run a command as administrator (user "root"), use "sudo <command>".
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See "man sudo_root" for details.
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$ sudo apt update
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[sudo] password for test-user:
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Get:1 http://security.ubuntu.com/ubuntu jammy-security InRelease [129 kB]
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Hit:2 http://archive.ubuntu.com/ubuntu jammy InRelease
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Get:3 http://archive.ubuntu.com/ubuntu jammy-updates InRelease [128 kB]
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Get:4 http://archive.ubuntu.com/ubuntu jammy-backports InRelease [127 kB]
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Get:5 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages [1987 kB]
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Get:6 http://archive.ubuntu.com/ubuntu jammy-updates/main amd64 c-n-f Metadata [17.8 kB]
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Get:7 http://archive.ubuntu.com/ubuntu jammy-updates/universe amd64 Packages [1112 kB]
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Get:8 http://archive.ubuntu.com/ubuntu jammy-backports/main amd64 Packages [67.8 kB]
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Get:9 http://archive.ubuntu.com/ubuntu jammy-backports/universe amd64 Packages [28.8 kB]
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Fetched 3598 kB in 3s (1302 kB/s)
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Reading package lists... Done
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Building dependency tree... Done
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Reading state information... Done
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57 packages can be upgraded. Run 'apt list --upgradable' to see them.

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sudo deluser test-user sudo

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$ groups test-user
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test-user : test-user
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$ cat /etc/group | grep sudo
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sudo:x:27:userX