What is lockfile command in Linux?
DESCRIPTION. lockfile can be used to create one or more semaphore files. If lockfile can’t create all the specified files (in the specified order), it waits sleeptime (defaults to 8) seconds and retries the last file that didn’t succeed. You can specify the number of retries to do until failure is returned.
What does a .lock file do?
A LOCK file is a file used by various operating systems and programs to lock a resource, such as a file or a device. It typically contains no data and only exists as an empty marker file, but may also contain properties and settings for the lock. lock” extension for the original filename.
What is NPM lockfile?
What’s a Lock File? A lock file describes the entire dependency tree as it is resolved when created including nested dependencies with specific versions. In npm these are called package-lock. json and in yarn they are called yarn.
When to use lock files in a script?
The most common use of lock files is to ensure a second instance of a script does not run until the first is completed. Anytime you have multiple processes working with shared resources, using lock files will help avoid conflicts and race conditions. It is important to point out that a lot of programming languages use lock files.
How are lock files used in real world?
Here is a real world example of how lock files could be used. A colleague of mine wrote a script that uses rsync over ssh to synchronize his workstation home directory to a shared directory on a server. He set the cron job to run this script every hour.
What happens if LockFile doesn’t create a file?
If lockfile can’t create all the specified files (in the specified order), it waits sleeptime (defaults to 8) seconds and retries the last file that didn’t succeed. You can specify the number of retries to do until failure is returned. If the number of retries is -1 (default, i.e., -r-1) lockfile will retry forever.
How to get lock on file descriptor 100?
The “|| exit 1” instructs the script to exit if the exec command fails. The above line obtains a lock on file descriptor 100. Basically holding a lock on the file until the shell closes. Since scripts run in a sub-shell, the file will be closed (or unlocked) when the script exits.