Re: Locking
Re: Locking
- Subject: Re: Locking
- From: Gwynne <email@hidden>
- Date: Wed, 16 Jun 2004 07:05:56 -0400
On Jun 16, 2004, at 6:44 AM, Wade Tregaskis wrote:
Under Classic MacOS you could find out which app had exclusive access
to a file, although I don't know how; I only know that many
applications (including the Finder) displayed this information at
various times. It was particularly handy when you had a removable
volume mounted and wanted to know why it can't be unmounted... under
OS X it just throws up some useless generic error message.
Try the 'lsof' command. It doesn't always work, but it's good most of
the time. The Finder and such don't use it for error messages because
it's setuid root (you need root privs to read kmem) and aside from
SecurityServer (Auth Services), the system's not in the practice of
habitually running setuid programs. Also, lsof is slow.
Although usually it's just Terminal, which for some reason prevents
most (all?) removable volumes being removed while it's open. Even
disk images and the like. Weird.
If you watch the output of the lsof command, you'll find that any
running process has it's current working directory open as a file
descriptor. This is designed, among other things, to prevent the system
from pulling the cwd out from under a process (though it can still
happen by moving the directory). If the cwd of a shell is on a
removable volume, that volume can't be unmounted until the shell cd's
to a directory on another filesystem.
-- Gwynne, key to the Code that runs us all
Formerly known as Sailor Quasar.
Email: email@hidden
Web:
http://musicimage.plasticchicken.com/
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| References: | |
| | >Locking (From: "Gerriet M. Denkmann" <email@hidden>) |
| | >Re: Locking (From: "Gerriet M. Denkmann" <email@hidden>) |