Lock file

File Format
Name	Lock file
Ontology	Electronic File Formats Temporary files Lock file
Extension(s)	.lck, .lock

Lock files are used to prevent simultaneous access to a specific file, device, or to prevent an application from being started twice. Lock files are found in Unix-like systems under the directory /var/lock (or more recently, /run/lock).

A lock file may be empty, but it usually contains the process ID of the program holding the lock.

Not to be confused with a File lock, although a lock file often has a file lock.

External links

• Lock files at Wikipedia