2

I see that

/home/user folder is created.
/etc/passwd file has an entry with non bin/false or bin/nologin shells.
/etc/group has user group.
/etc/shadow has the password.

Is there something else going on when adduser happens?

I would like to change ordinary user into a system user. And I'm trying to understand what is difference between this two, and what is created in each case by system tools.

  • what do you mean by system user – nux Apr 13 '14 at 7:48
  • @nux bin/false - one that cannot login, for services or daemons. – user25389 Apr 13 '14 at 7:49
  • you need also to know other options in adduser – nux Apr 13 '14 at 7:50
1

To know more about adduser options visit : Link

Well to change a user from ordinary user to system user use usermod -s option :

usermod -s /bin/false userName

I would suggest you also to visit : Site

bin/false :

Many times you will have a system where you need a user to exist in the account database (say, /etc/passwd) but don't want to give them shell access to your machine(s). A common solution to this is to set a user's shell to /bin/false. This has the effect of rejecting shell login attempts over ssh, telnet, or other shell-requesting protocols. It may have other side effects too, but those are beyond the scope of this article.

Simply using /bin/false as someone's shell does not keep them from using said account to authenticate over ssh and using non-shell tools such as port forwarding. A default configuration in sshd will often allow tunneling and other non-shell activity.

Reference

  • I was more curious what exactly command was doing on the system. But your answer is very clear in-depth answering many other questions I had. So what I wrote in OQ those are the only files affected? – user25389 Apr 13 '14 at 14:20
  • is my answer unclear? – nux Apr 13 '14 at 14:43
  • On the contrary, your answer was good, but it didn't answer my question directly: "When you create user using adduser what happens on the system?" – user25389 Apr 13 '14 at 20:29
0

Change a user? I dont know. But you can create a system user with no login and no home directory by issuing the following command :

sudo adduser --system --no-create-home

For more information, see the man for adduser.

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