flock

linux

Manage file locks from shell scripts. It can be used to ensure that only one instance of a command is running.

More info →

Options (3)

-n, --nonblockboolean

Run a command with a file lock, or exit if the lock is currently being held (with exit code 1)

Example: flock {{[-n|--nonblock]}} {{path/to/lock.lock}} {{command}}

-E, --conflict-exit-codeboolean

Run a command with a file lock, or exit with a specific error code if the lock is currently being held

Example: flock {{[-n|--nonblock]}} {{[-E|--conflict-exit-code]}} {{123}} {{path/to/lock.lock}} {{command}}

-w, --timeoutboolean

Run a command with a file lock, waiting up to 10 seconds for the lock to be available before giving up

Example: flock {{[-w|--timeout]}} 10 {{path/to/lock.lock}} {{command}}

Examples (5)

Run a command with a file lock as soon as the lock is available

flock path/to/lock.lock command

Run a command with a file lock, or exit if the lock is currently being held (with exit code 1)

flock [-n|--nonblock] path/to/lock.lock command

Run a command with a file lock, or exit with a specific error code if the lock is currently being held

flock [-n|--nonblock] [-E|--conflict-exit-code] 123 path/to/lock.lock command

Run a command with a file lock, waiting up to 10 seconds for the lock to be available before giving up

flock [-w|--timeout] 10 path/to/lock.lock command

Backup a bunch of files, waiting for the previous `tar` command to finish if it's still running elsewhere and holding the same lock file (can be used in a `cron` job that runs often)

flock path/to/backup.lock tar -cvf path/to/backup.tar path/to/data/

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