flock

Flock is a command line tool primarily used in Unix-like operating systems. It is designed to manage file locks, which are used to control access to files by multiple processes simultaneously.

Flock works by creating an advisory lock, which means it does not prevent other processes from accessing the file, but rather provides a way for processes to coordinate their access.

This tool is commonly used in scripting and programming to ensure that only one instance of a particular script is running at a time, to avoid conflicts and data corruption.

Flock provides options to control the behavior of locks, such as non-blocking mode (which immediately returns if the lock cannot be acquired) or exclusive mode (which allows only one process to lock the file).

In addition to file locking, flock also supports record locks, which allow locking specific regions of a file rather than the entire file.

Flock is often used in combination with other command line tools and utilities, such as cron (a time-based job scheduler) or shell scripts.

The basic syntax of flock is: flock [options] lockfile command, where lockfile is the file to be locked and command is the command to be executed.

Flock can be used with various file types, including regular files, directories, and NFS (Network File System) files.

If a process holding a lock terminates, the lock is automatically released, ensuring that other processes can acquire the lock.

Overall, flock provides a straightforward and efficient way to synchronize access to files and avoid conflicts between multiple processes.