How Linux disables accounts and disables accounts

There are several ways to disable your account:
1. # usermod-l <username>
    # usermod-u <username>                //de-disable
2. Modify the/etc/passwd file, there can be several places
1) Change the "X" in the second field to another character, and the account will not be able to log in
2) Change the/bin/bash into/sbin/nologin
3. Modify the/etc/shadow file
1) in the second password field before adding a "!", the account will not be able to log in, this is actually the result of the usermod-l command
2) Add the number "1" between the last two colons, indicating that the password for the account expires immediately after one day from January 1, 1970, and of course it is not possible to log in now.
If you want to lift the ban, remove the modified things.

How Linux disables accounts and disables accounts