0

Referencing the answers to this question, they give nifty one-liners to create such a user such as:

sudo adduser --system --no-create-home --group mightydog

After this, can user mightydog log on? What is his password?

Maki
  • 121
  • 7
Organic Marble
  • 23,641
  • 15
  • 70
  • 122

1 Answers1

5

There's no harm in simply trying it out. On my system (16.04), this resulted in a user with locked password (*) and no valid login shell (/bin/false), as can be seen from its /etc/passwd and /etc/shadow entry:

# grep mightydog /etc/passwd
mightydog:x:128:138::/home/mightydog:/bin/false

# grep mightydog /etc/shadow
mightydog:*:17610:0:99999:7:::

So no, it does not have a password, and it also can not log in by any other means (like SSH keys, or using sudo -u) due to the /bin/false shell.

Byte Commander
  • 107,489
  • Thanks. I'll need to investigate how to allow this user to log on via ssh. I appreciate your adding that bit of info, it saved me a lot of blind alley wandering. – Organic Marble Mar 20 '18 at 14:19
  • You just have to specify a login shell like /bin/bash and you should be able to log in using sudo -u or SSH after setting up key-based authentication. – Byte Commander Mar 20 '18 at 14:31
  • Thanks again. From what I've seen so far, I may also need to set up a minimal home directory to hold the .ssh directory for the user. But this I will be experimenting with. – Organic Marble Mar 20 '18 at 14:37
  • 2
    FYI this behavior is documented in the adduser manpage under Add a system user: "The new system user will have the shell /bin/false (unless overridden with the --shell option), and have logins disabled." – steeldriver Mar 20 '18 at 15:05