Re: Can you delete a file by descriptor?

is there a way to delete a file by descriptior or filehandle?

Not on *nix, and not, as far as I know, on Win32.

I'm afraid that a process might get wedged and lock out all programs using it.

Instead of wrapping a process around flock(), consider using a socket-based lock server, with "locks" recorded strictly in memory. Such a thing can be very simple, and very stable.

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Re: Re: Can you delete a file by descriptor? by shotgunefx (Parson) on Mar 14, 2002 at 08:15 UTC
Thanks for the tip. I was kind of thinking along those lines when I ran into the dead end with unlink. It's either that or making the script set uid as user lock or something, but then I'll have to wrap up the script in a c program. I guess the big plus with the sockets approach would be the ease of using it over the network albiet at a small performance hit. Whatever I come up with I'll post here. Thanks! -Lee "To be civilized is to deny one's nature."	[reply]
Re: Re: Can you delete a file by descriptor? by theorbtwo (Prior) on Mar 14, 2002 at 19:37 UTC
It's possible, at least on linux, if you don't mind cheating a little. Find /proc/pid/fd/n, and readlink it. That will give you /a/ (not neccessarly the only) name of the file opened on that fd. (Careful, though, because it will sometimes give things that are not filenames, like socket:n and /foo/bar (deleted). However, the other ideas on this thread are almost undoubtedly better. (I know several other unixes have similar proc (or proclike) filesystems, and many of them can probably be used similarly. Win32 doesn't, but you can do internals things to get the names from the handles. I wouldn't recommend it.) We are using here a powerful strategy of synthesis: wishful thinking. -- The Wizard Book	[reply]
Re3: Can you delete a file by descriptor? by blakem (Monsignor) on Mar 14, 2002 at 20:05 UTC
Thats pretty slick... I like it. You can get the same info from /dev/fd/n as well. `% perl -e'open($fh,"/tmp/file"); print readlink("/dev/fd/" . fileno($f +h))' /tmp/file` [download] -Blake	[reply] [d/l]
Re: Re3: Can you delete a file by descriptor? by theorbtwo (Prior) on Mar 15, 2002 at 15:44 UTC
Nod. (BTW, this works because /dev/fd/ is a symlink to /proc/self/fd/, and /proc/self is (magicly) a symlink to /proc/(pid) for whatever process is following the link. We are using here a powerful strategy of synthesis: wishful thinking. -- The Wizard Book	[reply]