Setting an exclusive lock on a file

[Eugene Perederey]

Hi all,
I want to set an exclusive lock on a file so other processes wouldn't
be able to write to it.
So I write

import fcntl
fd=open('myfile','w')
fcntl.lockf(fd, fcntl.LOCK_EX)
fd.write('some bytes')
fd.close()

But it turns out that my script doesn't write anything to file whereas
other processes do. What's wrong in my code?

 

[Diez B. Roggisch]

Hi all,
I want to set an exclusive lock on a file so other processes wouldn't
be able to write to it.
So I write

import fcntl
fd=open('myfile','w')
fcntl.lockf(fd, fcntl.LOCK_EX)
fd.write('some bytes')
fd.close()

But it turns out that my script doesn't write anything to file whereas
other processes do. What's wrong in my code?

http://code.activestate.com/recipes/65203/

Diez

 

[Diez B. Roggisch]

Hi all,
I want to set an exclusive lock on a file so other processes wouldn't
be able to write to it.
So I write

import fcntl
fd=open('myfile','w')
fcntl.lockf(fd, fcntl.LOCK_EX)
fd.write('some bytes')
fd.close()

But it turns out that my script doesn't write anything to file whereas
other processes do. What's wrong in my code?

Sorry, my other answer wasn't complete.

The "problem" with file-locking is that it's AFAIK cooperative. Just
because *you* lock a file doesn't mean anybody else is stopped from
using it.

I'm not sure if there is something else to overcome this.

Diez