How to change password offline via chroot or any other method?

Question

My friend did not use his (dual-boot) Linux Mint 20 in a long while, and forgot password to his system.

How can one change password offline, connecting his SSD to my Debian OS, I suppose likely via chroot, or any method really?

Vlastimil Burián · Accepted Answer · 2024-10-30 22:27:04Z

So, in my case, I have several directories in my /mnt, so I created directory /mnt/user
```
mkdir /mnt/user
```
Then, I mounted his ext4 partition with (note, I used this path as I am more used to it, of course, you can use e.g. /dev/sdXn, whichever you prefer:
```
mount /dev/disk/by-id/ata-<long_name>-part2 /mnt/user
```
It mounted ok, so I allowed myself to chroot into his system with:
```
chroot /mnt/user /bin/bash
```
Since the above step went ok too, I simply issued the change password commands, both for his username, and root:
```
passwd username
passwd root
```
I put his disk back into his machine and verified I can log in. Done.

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