Setting up a new user

2024-04-19T04:29:26Z

Vptr:

The <code>root</code> account should be used only for local administrative purposes that require elevated access permissions.

This page shows how to create non-privileged user accounts. i.e. those used for daily work, including desktop use and remote logins.

= Overview =

Creating user accounts provides users with their own {{path|$HOME}} directory and allows you (the root user) to limit the access those user accounts have to the operating system configuration files.

Using them increases security, because they limit possible actions and thus possible damage (even from accidental errors).

= Creating a new user =

{{Warning|If using a '''"diskless" or "data" disk mode''' installation, it's important to make the <code>/home</code> directory persistent.
<br>
* Either the <code>/home</code> filesystem needs to be mounted from a writable partition, or
* the /home directories have to be added to the lbu backup, and a new local backup needs to be committed after creating the user:
{{Cmd| # lbu include /home
# lbu commit
}} (Not recommended, as reverting to an older .apkovl will also revert the files in /home).
}}

Regular user accounts can be created with:
{{Cmd|# adduser [-g "<Full Name>"] <username>}}

By default, <code>adduser</code> will:
* prompt you to set a password for the new user
* create a home directory in {{Path|/home/<username>}}
* set the shell to the one used by the <code>root</code> account (ash by default)
* assign user ID and group ID starting at 1000
* set the GECOS (full name) field to "Linux User,,,"

{{Tip|The optional <code>-g "<Full Name>"</code> above sets the GECOS field.
This can be very useful to specify. Setting this string - at least equal to the username - makes the user distinguishable, e.g. when they are listed at the login screen of a display manager.
}}

'''If a user ''really must'' be allowed to have access to the root account''', the <username> can be added to the '''wheel''' group and <code>{{Pkg|doas}}</code> ("do as") may be installed:
# adduser -g "<username>" <username>
# adduser <username> wheel
# apk add doas

You will want to allow members of the '''wheel''' group to use root privileges with <code>doas</code>. To do this, open the <code>doas</code> config file:

{{Cmd|# <editor> /etc/doas.d/doas.conf}}

Add the following line and save the file:
{{Cmd|permit persist :wheel}}

{{Warning|It's recommended to '''not''' run complete applications, like editors, as root just to modify administrative files.
<br>
* [https://github.com/AN3223/scripts/blob/master/doasedit <code>doasedit</code>] or <code>sudoedit</code>([https://wiki.alpinelinux.org/wiki/Release_Notes_for_Alpine_3.15.0#Move_from_sudo_to_doas being deprecated in favour of <code>doas</code>]) enables starting an editor with a temporary copy of a file, which overwrites the original file after the user modifies and saves it. For example, <code>sudoedit /etc/apk/lbu.conf</code>
* Many desktop environments and file browsers support using <code>admin:///</code> in their address bars, to access files through a local gvfs-admin mount.
}}
The <code>sudo</code> package is an alternative to using the BSD-like <code>doas</code>, but is a much larger package.
It may be used as follows: adding a custom user configuration file to avoid having to deal with manually changing configuration files later during package upgrades.
apk add sudo
NEWUSER='yourUserName'
adduser -g "${NEWUSER}" $NEWUSER
echo "$NEWUSER ALL=(ALL) ALL" > /etc/sudoers.d/$NEWUSER && chmod 0440 /etc/sudoers.d/$NEWUSER

<br>

If no seat manager like [[elogind]] or [[seatd]] is being used and running, then users that want a graphical environment need the '''video''' and '''input''' groups:
# adduser '<username>' video
# adduser '<username>' input

The above is highly discouraged. See {{Issue|15409}}.

The new user gets listed in

{{Cat|/etc/passwd|root:x:0:0:root:/root:/bin/ash
.
.
.
<username>:x:1000:1000:<username>:/home/<username>:/bin/ash}}

Now you should be able to issue the command <code>exit</code> and login to the new account.

= Options =

=== adduser ===

Usage (from "man busybox"):

<pre><nowiki>adduser [OPTIONS] USER [GROUP]

Create new user, or add USER to GROUP

-h --home DIR Home directory
-g --gecos GECOS GECOS field
-s --shell SHELL Login shell named SHELL by example /bin/bash
-G --ingroup GRP Group (by name)
-S --system Create a system user
-D --disabled-password Don't assign a password, so cannot login
-H --no-create-home Don't create home directory
-u --uid UID User id
-k SKEL Skeleton directory (/etc/skel)
</nowiki></pre>

{{Tip|Multi-user collaboration
If <nowiki>--ingroup</nowiki> isn't set, (default) the new user is assigned a new GID that matches the UID. If the GID corresponding to a provided UID already exists, adduser will fail.

This ensures new users default to having a "user's private group" (UPG) as primary group. These allow the system to use a permission umask (002), which creates new files automatically as group-writable, but only by the user's private group. In special set-group-id (collaboration) directories, new files can be automatically created writable by the directory's group.
}}

=== addgroup ===

Usage (from "man busybox"):

<pre><nowiki>addgroup [-g GID] [-S] [USER] GROUP

Create a group or add a user to a group

-g --gid GID Group id
-S --system Create a system group
</nowiki></pre>

= Home directory permissions =

`adduser` creates home directories with permissions `rwxr-sr-x`. This makes the directory readable by all other users on the system. If you prefer to not allow other users to read your home directory, the permissions can be changed:

{{Cmd| chmod o-rx <path-to-directory>}}

= Legacy =

=== Common permission groups ===

{{Draft|Need to note a few security implications outlined on [https://wiki.debian.org/SystemGroups debian/wiki SystemGroups]}}

Groups are needed for certain operations on your system.

(Names taken from https://git.alpinelinux.org/alpine-baselayout/tree/group)

{{Cmd|adm Used for system monitoring tasks.
disk Raw access to disks. '''Mostly equivalent to root access.'''
lp Members of this group can enable and use printers.
wheel Administrator group, members can use '''doas''' to run commands as root if enabled in the doas configuration.
floppy Access to floppy drives and other removable (non-optical) drives (like USB flash drives).
audio Direct access to sound hardware (the soundcard or a microphone).
cdrom For access to disk writers and mounting DVD, BR or CD-ROM disk as normal user.
dialout Full and direct access to serial ports.
input Access to input devices.
tape Needed to give a set of users access to a tape drive.
video Access to video capture devices (like a webcam).
netdev For network connections management as normal user.
kvm Needed to use the KVM acceleration of virtual machines.
games Access to some game software.
cdrw Needed to write RW-DVD, RW-BR or RW-CD disk on a disk writing device.
usb Needed to access special USB devices, deprecated group.
users Needed if you plan to used common files for all users, mandatory as desktop usage.}}

To add your user to a group use the following command:
{{Cmd|# adduser <username> <group>}}
{{Note|You need to log out for the group change(s) to take effect.}}

To see what group(s) a <username> is in, use the following command:
{{Cmd|# id <username>}}

= Old newbie notes =

=== User creation and defaults ===

The following commands will set up root environment login, then assign a new password:

<pre><nowiki>
cat > /root/.cshrc << EOF
unsetenv DISPLAY || true
HISTCONTROL=ignoreboth
EOF

cp /root/.cshrc /root/.profile

echo "secret_new_root_password" | chpasswd
</nowiki></pre>

By default, remote management cannot be done directly with the root account. Because of SSH security we need to set up a remote connection account that will be used to switch to the root user via the su command, once connected.

Here's an example: create user named "remote" and a user named "general". We will set up a hardened, limited, user environment and create those two users:

<pre><nowiki>
mkdir -p /etc/skel/

cat > /etc/skel/.logout << EOF
history -c
/bin/rm -f /opt/remote/.mysql_history
/bin/rm -f /opt/remote/.history
/bin/rm -f /opt/remote/.bash_history
EOF

cat > /etc/skel/.cshrc << EOF
set autologout = 30
set prompt = "$ "
set history = 0
set ignoreeof
EOF

cp /etc/skel/.cshrc /etc/skel/.profile

adduser -D --home /opt/remote --shell /bin/ash remote

echo "secret_new_remote_user_password" | chpasswd

adduser -D --shell /bin/bash general

echo "secret_new_general_user_password" | chpasswd
</nowiki></pre>

{{Tip|"'''general'''" is the name of the user. That name MUST contain ONLY lowercase letters, NO spaces and NO symbols}}

Note that those users are created with minimal privilege settings.

== User management and system access ==

By default, a newly created user will not have enough privileges for most desktop purposes.

To add newly created users to groups that may come in handy for desktop useage, you run this command as root:

{{cmd|for u in $(ls /home); do for g in disk lp floppy audio cdrom dialout video netdev games users; do addgroup $u $g; done;done}}

== See also ==

* [https://wiki.archlinux.org/title/Users_and_groups Users and groups - Archwiki]

[[Category: System_Administration]]

Alpine Linux - User contributions [en]

Setting up a new user