File::LockDir is a Perl basic filename-level lock utility.
Initializes the class. Returns the singleton object.
nflock($file, $nap_till, $locker, $lockhost)
Locks the supplied filename. Only $file is required.
$file is the file to be locked; $nap_till is the total amount of time to wait before giving up; $locker is a name identifying the locker; $lockhost is the host requesting the lock.
Unlocks the supplied file.
Checks the state of the lock for the supplied file. Returns a list: the first item is true if the file is unlocked, and false if not; the second item is undef if the file is unlocked, and the identity (name and host) is it is locked.
%s already locked
Seen when you've already locked the requested pathname. Informational only.
No pathname to be locked
You didn't supply a pathname to be locked to nflock. Fatal.
can't write to directory of %s
The directory where the file resides can't be written, so the lockfile can't be created.
can't get %s: %s
The named lock can't be gotten: the reason is supplied. Failure occurs after ten tries to get the lock.
%s %s[%s]: lock on %s held by %s
The lock on the specified file is help by the noted locker. Informatory message, printed only when debugging is on.
close failed for %s: %s
The file containing the lock information couldn't be closed for the reason shown.
releasing lock on %s
Debug message; notes that the lock on the specified file was successfully released.