Using the `ac` command to Print Statistics on User Connections (with examples)

The ac command in Linux is a powerful tool that provides statistics on how long users have been connected to the system. It can be used to analyze user activity and monitor system usage. In this tutorial, we will explore eight different use cases of the ac command and explain the code, motivation, and arguments for each use case.

1. Print how long the current user has been connected in hours

ac

Motivation: This use case is helpful when you want to quickly check how long the current user has been connected to the system. It can be useful for monitoring your own usage or when troubleshooting login issues.

Explanation: This command without any arguments simply displays the total login time for the current user. The output shows the total number of hours (rounded to two decimal places) that the user has been logged in.

Example Output:

    total       12.23

2. Print how long users have been connected in hours

ac --individual-totals

Motivation: This use case is useful when you want to view the login time of all users on the system. It can help in detecting excessive usage or identifying idle user sessions.

Explanation: The --individual-totals option is used to display the login time for each individual user on the system. The output will show the total number of hours (rounded to two decimal places) that each user has been logged in.

Example Output:

    john       5.67
    mary       2.43
    guest      1.11

3. Print how long a particular user has been connected in hours

ac --individual-totals username

Motivation: This use case is handy when you want to check the login time of a specific user on the system. It can be useful for monitoring the activity of specific users or reviewing their usage patterns.

Explanation: Replace username with the actual username of the user you want to get the login time for. This command with the --individual-totals argument will display the login time of the specified user in hours (rounded to two decimal places).

Example Output:

    john       5.67

4. Print how long a particular user has been connected in hours per day (with total)

ac --daily-totals --individual-totals username

Motivation: This use case is helpful when you want to analyze the login time of a specific user on a daily basis. It can give you insights into their usage patterns, such as peak login hours or days of low activity.

Explanation: This command combines the --daily-totals and --individual-totals options to display the login time of a particular user per day, along with the total login time. Replace username with the actual username of the user.

Example Output:

    day          hours
    Monday       1.50
    Tuesday      0.75
    Wednesday    3.00
    ...
    Total        12.56

5. Also display additional details

ac --compatibility

Motivation: This use case is useful when you want to get more detailed information along with the login time. It can provide additional insights into the user accounts, such as the number of sessions and the number of commands executed.

Explanation: The --compatibility option enables the display of additional details like the number of sessions and the number of commands executed for each user. This option enhances the output of the ac command, making it more informative.

Example Output:

    john (1000)     5.67     25     230
    mary (1001)     2.43     15     160
    guest (1002)    1.11     5      50

In this example output, the second column represents the login time in hours, the third column indicates the number of sessions, and the fourth column shows the number of commands executed.

Now you have learned eight different use cases of the ac command, ranging from printing the login time for the current user to obtaining detailed statistics for individual users. These examples can help you monitor user activity, identify excessive usage, and gain insights into system usage patterns.