2008-02-14 09:45:55

by Tom Van Looy

[permalink] [raw]
Subject: Re: Is there a

You can create a symlink to /dev/null and name it whatever you want?

$ ln -s /dev/null tempfile
$ echo blablabla > tempfile
$ wc tempfile
0 tempfile




>----- Oorspronkelijk bericht -----
>Van: rzryyvzy [mailto:[email protected]]
>Verzonden: donderdag, februari 14, 2008 10:30 AM
>Aan: [email protected]
>Onderwerp: Is there a "blackhole" /dev/null directory?
>
>Hello Linux Kernel Hackers,
>
>/dev/null is often very useful, specially if programs force to save data in some file. But some programs like to creates different temporary file names, so /dev/null could no more work.
>
>What is with a "/dev/null"-directory?
>I mean a "blackhole pseudo directory" which eats every write to null.
>
>Here is how it could work:
>mount -t nulldir nulldir /dev/nulldir
>
>Now if a program does a create(2),
>it creates in the memory the file with its fd.
>Then if a program does a write(2) to the fd, it eats the writes and give out fakely it has written the number of bytes.
>When the program calls does a close(2) of the fd, then the complete inode is deleted in the memory.
>
>The directory should be permanently empty except for the inodes with open file descriptors. So only inode information would be temporary saved in this "nulldir tmpfs" directory.
>
>Is there already existing a possibility to create a null directory?
>--
>Best regards,
>Mika Lawando
>
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2008-02-14 12:12:41

by rzryyvzy

[permalink] [raw]
Subject: Re: Is there a

Tom Van Looy schrieb:
> You can create a symlink to /dev/null and name it whatever you want?
>
> $ ln -s /dev/null tempfile
> $ echo blablabla > tempfile
> $ wc tempfile
> 0 tempfile
>
The problem is, what do you do if the filename would be:
tempfile.<TIMESTAMP>

where <TIMESTAMP> is replaced by the unix timestamp. I mean how do you
redirect to /dev/null if you don't know in advance the filename your
application will create.

Its true the quick way would be to write a filesystem in Perl with fuse.
But it would be better to implement this natively in the kernel, because
there is a loss of performance in fuse between the communication of the
fuse client and the fuser server (it uses a socket mechanism).

--
Best regards,
Mika Lawando