flock

Manage locks from shell scripts. It can be used to ensure that only one process of a command is running. More information: https://manned.org/flock.

• Run a command with a file lock as soon as the lock is not required by others:
  flock {{path/to/lock.lock}} --command "{{command}}"
• Run a command with a file lock, and exit if the lock doesn't exist:
  flock {{path/to/lock.lock}} --nonblock --command "{{command}}"
• Run a command with a file lock, and exit with a specific error code if the lock doesn't exist:
  flock {{path/to/lock.lock}} --nonblock --conflict-exit-code {{error_code}} -c "{{command}}"