Home : File Types : LOCK File (2 File Associations)

.LOCK File Extension

File Type 1Lock File

4.1 (41 Votes)
CategoryMisc Files
FormatText and Binary

Text and Binary

This file is saved in a plain text format or a binary format. If in a plain text format, it can be viewed with a text editor.

What is a LOCK file?

File used by various operating systems and programs to lock a resource, such as a file or a device; typically contains no data and only exists as an empty marker file, but may also contain properties and settings for the lock.

More Information

LOCK files signal to applications that a resource should not be used until the lock is released. This is useful for programs that need to prevent concurrent access to critical resources. For file locking, programs typically create a new file and add the ".lock" extension for the original filename. For example, a lock file for "example.file" would be "example.file.lock."

LOCK files are commonly seen on Unix-based systems, including Red Hat Linux system file locks. Other examples of LOCK files include Mozilla's parent.lock file, which locks Windows Firefox profiles, and Apache Web Server lock files, which are created using the LockFile directive.

Open over 300 file formats with File Viewer Plus.
Programs that open LOCK files
Updated 8/15/2013

File Type 2Minecraft World Lock File

DeveloperMojang Specifications
3.1 (12 Votes)
CategoryGame Files


This file is saved in a binary format, which requires a specific program to read its contents.

.LOCK File Association 2

Lock file named session.lock and used by Minecraft, an open-ended block construction game; included as part of the data for a Minecraft world; enables a Minecraft application to lock the world so that only one Minecraft instance has it open; saves a timestamp for when the world was last accessed.

More Information

Minecraft uses a locking policy such that the last instance to open the world is the world owner. If the contents of the session.lock file change after an instance has written its timestamp, the instance aborts and gives up the lock.

Programs that open LOCK files
Updated 4/22/2011

About LOCK Files

Our goal is to help you understand what a file with a *.lock suffix is and how to open it.

All file types, file format descriptions, and software programs listed on this page have been individually researched and verified by the FileInfo team. We strive for 100% accuracy and only publish information about file formats that we have tested and validated.

If you would like to suggest any additions or updates to this page, please let us know.