How does file locking work in Linux?

resetreset · 04-21-2011, 01:25 PM

I have a situation in an office where a LAN will be installed - what I want to know is, after that, can 2 people open the same spreadsheet file, i.e. the person on the computer that it's on, as well as somebody across the LAN?

Thanks.

poorsod · 04-21-2011, 02:35 PM

Quote:

Originally Posted by resetreset

I have a situation in an office where a LAN will be installed - what I want to know is, after that, can 2 people open the same spreadsheet file, i.e. the person on the computer that it's on, as well as somebody across the LAN?

Thanks.

Linux lets you use file locking, or not. It's up to the programmer basically. If you're using a spreadsheet Open Office :

Quote:

If you are working on a network where several people may have access to the same document, file locking prevents people accidentally overwriting other people's changes. As OpenOffice.org works on different operating systems, it cannot rely on the operating system alone to tell users when a document is in use. OpenOffice.org now has its own mechanism, which allows it to have a reliable locking when the locking from the operating systems fails.

It's only written to when the user clicks 'save' and that's pretty brief. Without locking if one guy saved something, then another guy saved something, that second guy would overwrite the first guys saved data. That's why openoffice uses locking - and it should!
I'm pretty sure anyone will be able to download/copy the file if they're accessing it with something like an ftp or samba server or something. But when it comes to writing to it the file, proper locking should be implemented by the program to prevent race-condition scenarios. That's all OS independent though.

spankbot · 04-21-2011, 06:40 PM

Quote:

Originally Posted by resetreset

I have a situation in an office where a LAN will be installed - what I want to know is, after that, can 2 people open the same spreadsheet file, i.e. the person on the computer that it's on, as well as somebody across the LAN?

Thanks.

Two people will be able to open the file at the same time with no problems. The issues comes when two people try to save the file at the same time. As a poster above correctly points out, this is called a "race condition". This isn't a Linux specific issue - all networkable OS's have to deal with this.

If you need to allow more than one person to edit and change a file, you should implement some sort or version control system, like Git (http://git-scm.com/) or Subversion (http://subversion.apache.org/).

resetreset · 04-22-2011, 12:58 AM

Quote:

Originally Posted by spankbot

Two people will be able to open the file at the same time with no problems.

Will there be any message popping up to say that the file is already in use by someone else? (like happens in Windoze)?

spankbot · 04-22-2011, 03:05 PM

Quote:

Originally Posted by resetreset

Will there be any message popping up to say that the file is already in use by someone else? (like happens in Windoze)?

Possibly. Depends on the software being used to open the file, how the network is setup, are you using nfs, etc.

If it were two people on the same computer, using VI to open the file, then in that particular scenario you would get a warning...

Sounds like you really need some sort of version control. A Subversion server would take care of these issues for you. And your users would be able to use what ever OS they wanted as there are subversion clients for all platforms.