flock: bad number: myfile.lock

Question

I try to put a lock on a file like this:

flock -e myfile.lock

The result is:

flock: bad number: myfile.lock

Doesn't matter whether file exist or not, or whether I'm root. I even tried chmod a+rwx myfile. Still get the same error. I tried the same not on my machine but on Debian and I get the same error...

Answer 1

The command is missing. Try:

flock -e myfile.lock ls

The number is the file descriptor of the usage alternativ:

(
  flock -e 200
  ls
) 200>myfile.lock

See the man page.