Sometimes the best way to troubleshoot and operating system, application, or service is to consult the log file(s) that app or service generates as it goes about its business. But what is a LOG file and how do you see what’s in it?

What Is a Log File?

LOG is the file extension for an automatically produced file that contains a record of events from certain software and operating systems. While they can contain a number of things, log files are often used to show all events associated with the system or application that created them. For example, your backup program might keep log files showing exactly what happened (or didn’t happen) during a backup. Windows keeps all kinds of log files for its various services.

The point of a log file is to keep track of what’s happening behind the scenes and if something should happen within a complex system, you have access to a detailed list of events that took place before the malfunction. Basically, whatever the application, server, or OS thinks needs to be recorded.

While most log files contain the .log file extension, sometimes applications may use the .txt extension or a different proprietary extension, instead.

How Do I Open One?

Because most log files are recorded in plain text, the use of any text editor will do just fine to open it. By default, Windows will use Notepad to open a LOG file when you double-click on it.

You almost certainly have an app already built-in or installed on your system for opening LOG files. To start with, if you’ve got any word processing app installed—Microsoft Word, LibreOffice, OpenOffice, Notepad++, and so on—you can open a LOG file with it.

If you don’t have a text editor, some web browsers support viewing of log files as well. All you have to do is drag and drop the file you want to open into a new tab.

Your browser will then display everything contained in the file in the new tab.

If you prefer that LOG files open with a different program than the current default, you can change it. On both Windows or macOS, just right-click the file and select the “Open With” command for picking the program you want to use.

Here’s the window that will pop up in Windows (macOS is similar) after you click that. All you have to do next is choose the program you want to use, select “Always Use This App To Open .LOG Files”, and click “OK”.

Also keep in mind that some operating systems and applications have their own tools for viewing logs they generate. For example, events logged by Windows and many different Windows apps are more easily viewable in Event Viewer—a tool that lets you search your way and troubleshoot through all kinds of different Windows issues.

RELATED: What Is the Windows Event Viewer, and How Can I Use It?


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Brady Gavin has been immersed in technology for 15 years and has written over 150 detailed tutorials and explainers. He's covered everything from Windows 10 registry hacks to Chrome browser tips. Brady has a diploma in Computer Science from Camosun College in Victoria, BC.  
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