Listing Users on Ubuntu via WSL for UltraLinux

This guide provides step-by-step instructions for listing users on Ubuntu using the Windows Subsystem for Linux (WSL) on a Windows system, tailored for users interested in the UltraLinux project (https://ultralinux.org/). While UltraLinux focuses on Linux for SPARC processors, this tutorial helps users explore user management commands in a Linux-like environment on Windows using WSL. These commands are useful for system administration tasks, which are relevant for UltraLinux environments.

Prerequisites

A Windows 10 or 11 system with WSL2 enabled.
Basic familiarity with terminal commands.
Internet access to install packages if needed.

Step 1: Enable and Install WSL2

Enable WSL2:
- Open PowerShell as Administrator and run:
```
wsl --install
```
- This enables WSL and installs Ubuntu by default. Restart your computer if prompted.
- Alternatively, enable WSL manually:
  - Go to Settings > Apps > Optional Features.
  - Select Windows Subsystem for Linux, click OK, and restart.
Install Ubuntu:
- From the Microsoft Store, search for “Ubuntu” (e.g., Ubuntu 22.04 LTS) and click Install.
- Launch Ubuntu from the Start menu and set up a username and password when prompted.
Set WSL2 as Default:
- In PowerShell, run:
```
wsl --set-default-version 2
```
- Verify Ubuntu is using WSL2:
```
wsl -l -v
```

Step 2: Update Ubuntu

Update Ubuntu:
- Open the Ubuntu terminal and update the package list:
```
sudo apt update && sudo apt upgrade -y
```

Step 3: Commands to List Users

Below are key commands to list users on Ubuntu in WSL. These commands are applicable to user management in UltraLinux environments, though WSL may show fewer users due to its virtualized nature.

List Users with getent:
- Display all users from the system’s user database:
```
getent passwd
```
- This lists user details, including username, UID, GID, home directory, and shell. Each line represents a user, e.g., username:x:1000:1000::/home/username:/bin/bash.
List Users with cut and /etc/passwd:
- Extract usernames from the /etc/passwd file:
```
cut -d: -f1 /etc/passwd
```
- This displays only usernames, one per line, making it easier to read.
List Users with compgen:
- Use the bash built-in compgen to list users:
```
compgen -u
```
- This provides a simple list of usernames, similar to the cut command.
Check Current User:
- Display the currently logged-in user:
```
whoami
```
- Alternatively, show details of the current session:
```
who
```
List Users in a Specific Group:
- View users in a specific group (e.g., sudo group):
```
getent group sudo
```
- This shows the group name and its members, e.g., sudo:x:27:username.
List All Groups and Members:
- Display all groups and their members:
```
getent group
```
- This lists all groups, with user membership details.

Step 4: Create and Run a Test Script

To automate user listing, you can use a shell script. This is useful for UltraLinux users managing SPARC systems where user management is critical.

Create a Shell Script:

Create a file named list_users.sh:
```
nano ~/list_users.sh
```

Add the following code:

#!/bin/bash
echo "Listing Users for UltraLinux Environment"
echo "---------------------------------------"
echo "1. Current User (whoami):"
whoami
echo
echo "2. All Users (cut /etc/passwd):"
cut -d: -f1 /etc/passwd
echo
echo "3. Users with Details (getent passwd):"
getent passwd
echo
echo "4. Sudo Group Members (getent group sudo):"
getent group sudo
echo
echo "For more group details, run 'getent group' manually."

Make the Script Executable:
- Set execute permissions:
```
chmod +x ~/list_users.sh
```
Run the Script:
- Execute the script:
```
./list_users.sh
```
- The script outputs a summary of users and group membership. Some commands (e.g., getent) may require sudo for full access.

Step 5: Additional Tips for UltraLinux Users

SPARC Considerations: On SPARC hardware for UltraLinux, these commands directly apply to user management. In WSL, the user list may be limited due to virtualization, but the commands are identical. Test on a native SPARC system for accurate results, and consult UltraLinux documentation (https://ultralinux.org/) for SPARC-specific user management.
User Management: For UltraLinux systems, ensure proper user permissions for SPARC hardware access. Use getent to verify user and group configurations.
Community Resources: For UltraLinux-specific user management questions, refer to the mailing lists or FAQ on https://ultralinux.org/.
Security Monitoring: To monitor user activity, consider installing last to view login history:
```
sudo apt install last
last
```

Conclusion

You’ve now learned how to list users on Ubuntu via WSL using essential Linux commands, preparing you for user management tasks relevant to UltraLinux. These commands help manage user accounts, which are critical for system administration on SPARC-based systems. For further details, explore https://ultralinux.org/ for UltraLinux-specific resources, including mailing lists and the FAQ.