This article provides a comprehensive understanding of the Linux ‘last’ command, its history, usage, and common use cases. It emphasizes points to be cautious of and concludes with the importance of understanding the ‘last’ command.
Instructions
This article will provide a detailed understanding of the Linux ‘last’ command. It will delve into its history, its purpose, and how to use it, including its parameters. We will discuss common use cases, advanced tips, and important points to note, and wrap up with a conclusion.
History
The ‘last’ command has been a part of Unix/Linux operating systems for a long time, serving as an essential tool for system administrators to monitor user activity.
When and why to use it
The ‘last’ command is used when you need to check the login history in a Linux system. It displays the list of all users’ last logged in session and can help in auditing and monitoring user activities.
How to use it
To use the ‘last’ command, you simply type ‘last’ into the command line and press enter.
$ lastThe commonly used parameters
The ‘last’ command has several useful parameters:
-nThis parameter can limit the number of lines returned by the 'last' command.
$ last -n 5-aThis parameter displays the hostname in the last column, useful if you have users logging in from different locations.
$ last -aOther supported parameters
The ‘last’ command has other supported parameters as well, including:
-d— Displays the user's domain name.-F— Displays the full login and logout times and dates.-i— Displays IP instead of hostname.-R— Omits the display of the hostname.-w— Does not convert addresses to keep output clean.
Most common use cases
One common use case for the ‘last’ command is when investigating security incidents or user activity. For example, to find out the last few login attempts of a particular user.
$ last usernameThe tricky skills
An interesting skill with ‘last’ is using it in combination with other commands like ‘grep’ to filter the output. For instance, if you want to see only the logins from a particular user.
$ last | grep usernameWhat needs to be noted
The ‘last’ command reads the ‘/var/log/wtmp’ file. If this file is manipulated, the ‘last’ command’s output will be affected. System administrators should ensure that proper permissions are set on this file to avoid tampering.
Conclusion
Understanding and effectively using the ‘last’ command is crucial for anyone using Linux, especially system administrators. It provides valuable insight into user activity and aids in security and auditing efforts.
