finger Command in Linux

finger [options] [username]

Prerequisites to Use Linux Command finger

To start using finger command in Linux, your machine needs to meet all the below specifications:

• A Linux VPS running a compatible Linux distribution (e.g., Ubuntu, Debian, CentOS).
• A non-root user with sudo privileges.
• Access to Terminal/Command line.

Practical Examples to Learn finger Command in Linux

As a Linux system administrator or someone who manages users, it’s crucial to be familiar with various Linux commands such as finger command.

sudo apt-get install finger

sudo yum install finger

sudo dnf install finger

Now that the finger command is installed, let’s go through this tutorial to explore how to execute finger command in Linux with various options and the functionalities of this command with practical examples to enhance your command line experience.

1. Display Information of Currently Logged-in Users

One of the simplest uses of the finger command in Linux is to display information about all the users currently logged into the system.

• Syntax:

finger

Output

Login    Name            TTY      Idle    Login Time   Office
jdoe     John Doe        pts/0    10:34   Oct 10 09:30
mjane    Mary Jane       pts/1            Oct 10 09:45

The output will show a list of all logged-in users, including their login name, terminal, login time, and idle time. This is a quick way to get an overview of who is using the system.

2. Retrieve Information About a Specific User

You can use the finger command in Linux followed by a username to get detailed information about that user.

This includes login name, real name, home directory, shell, mail status, and the user’s plan.

• Syntax:

finger username

• Example:

finger opera

Output

Login: opera            Name: Opera
Directory: /home/opera  Shell: /bin/bash
On since Oct 10 09:20 (11 minutes ago) on pts/2
No mail.
Plan: New Plan

The output shows the opera’s full name, its home directory, the shell it is using, its login time, and its plan if it exists.

3. Display User Information in Short Format

If you want to see the user’s information in a more compact format, use the -s option.

This option organizes the data in a concise, tabular form, making it easy to scan through the information.

• Syntax:

finger -s username

• Example:

finger -s opera

Output

Login    Name            TTY      Idle    Login Time   Office
opera   Opera   pts/2            Oct 10 09:20

This short format gives essential details like the user’s login name, their terminal (TTY), idle time, and when they logged in.

4. Display Detailed Information Without .plan and .project Files

By default, the finger command in Linux shows the contents of the .plan and .project files located in a user’s home directory.

If you prefer not to display these, you can use the -p option, which suppresses this information.

• Syntax:

finger -p username

• Example:

finger -p opera

Output

Login: opera            Name: Opera
Directory: /home/opera  Shell: /bin/bash
On since Oct 10 09:20 (11 minutes ago) on pts/2
No mail.

As you see, the output omits the plan and project details.

5. Get Idle Status and Login Details of a User

If you’re managing system resources, knowing how long a user has been idle can be useful.

The finger command in Linux can show the idle status along with other login details.

• Syntax:

finger -s username

• Example:

finger -s opera

Output

Login    Name            TTY      Idle    Login Time   Office
opera   Opera   pts/2    10:45   Oct 10 09:20

As you see, in this example, Opera has been idle for 10 minutes and 45 seconds. This information is useful for monitoring user activity.

6. View User’s Plan and Project Information

Users can create a .plan and .project file in their home directory, which can be displayed using the finger command.

The .plan file typically contains notes about the user’s current tasks, while the .project file can describe their ongoing projects.

• To create a plan for the user, use the following commands:

echo "Working on Linux project" > ~/.plan
echo "Linux System Optimization" > ~/.project

Then, retrieve the user’s plan and project information using the finger command:

finger username

• Example:

finger opera

Output

Login: opera            Name: Opera
Directory: /home/opera  Shell: /bin/bash
On since Oct 10 09:20 (11 minutes ago) on pts/2
No mail.
Plan: Working on Linux project
Project: Linux System Optimization

This feature is helpful for system administrators or users collaborating in a project environment.

7. Prevent Matching the Full Name of a User

If you want to ensure that the finger command in Linux only matches usernames and not full names, use the -m option.

This is useful in situations where there might be ambiguity between usernames and full names.

• Syntax:

finger -m username

• Example:

finger -m opera

Output

finger: parker: no such user.

8. Create a Custom PGP Key for the User

You can also use the finger command in Linux to display a user’s PGP key, which is stored in the .pgpkey file in the home directory.

• Example:

cat > ~/.pgpkey

Once the file is created, the finger command will display its contents, making it a useful tool for showing public key information.

9. Display Information in Long Format

For a more detailed view, including additional system information like mail and login times, use the -l option to display the user’s information in long format.

• Syntax:

finger -l username

• Example:

finger -l opera

Output

Login: opera         Name: Opera
Directory: /home/opera  Shell: /bin/bash
On since Oct 10 09:20 (1 hour 30 minutes ago) on pts/2
Mail last read Sun Oct 1 14:32 2023 (3 days ago)
Plan: Working on kernel development.

The -l option provides additional information, including the exact login time, when mail was last read, and user plans or projects if available.

This can be especially useful for system administrators who need detailed user data.

Finger Command Options

At a glance, let’s review the common options for the finger command, including the syntax, description, and practical examples for each option.

What is “no such user” error when using finger with a username?

This error typically means that the username you entered doesn’t exist on the system, or you may have misspelled it.

Double-check the username and ensure that you are entering the exact username as it appears on the system.

If you want to avoid this error for partial matches (like matching full names), avoid using the -m option, which only looks for exact username matches.

Example:

finger -m Ashley  # Will only match the username "Ashley"

Use:

finger Ashley

Why does finger not show the .plan or .project file information for a user?

If the .plan or .project files are not displayed, it could be for several reasons:

• The user does not have these files created in their home directory.
• The files may not have the correct permissions to be readable.

To create a .plan or .project file, the user can run:

echo "My Plan" > ~/.plan
echo "My Project" > ~/.project

Run the command below to ensure the files are readable:

chmod 644 ~/.plan ~/.project

Then, to see the plan and project details, run:

finger <username>

How to stop finger from showing my .plan, .project, or .pgpkey file information to other users?

If you don’t want your .plan, .project, or .pgpkey to be displayed, you can remove read permissions for others:

Run the command below to hide the files from being viewed by others:

chmod 600 ~/.plan ~/.project ~/.pgpkey

How to troubleshoot the” finger Command Not Found” error?

This error means the finger package is not installed on your system. Install Linux command finger using the below commands:

sudo apt install finger  # For Ubuntu/Debian
sudo yum install finger  # For CentOS/RedHat

What are finger command security considerations?

Since the finger command in Linux can expose details such as user directories, login times, and custom notes, it’s recommended to disable the finger service on public-facing systems or restrict its usage to mitigate security risks.

To disable the finger service on your machine, run:

sudo systemctl disable finger

Conclusion

From checking logged-in users to displaying user plans and projects, the finger command in Linux has a wide range of practical applications for system administrators.

The examples in this guide explain how to effectively use different options of the finger command, helping you to retrieve specific user details, monitor activity, and manage resources efficiently.

Understanding and utilizing finger command in Linux is crucial for maintaining system security, tracking user sessions, and optimizing overall system management.