Locate a file by Inode - UNIX Programming

[S Derman]

This there a way with UNIX to locate a file by inode if you know the
inode information?

I'd like to do this on Darwin.

Thanx in advance for any help.

SD.

[Arto V. Viitanen]

>>>>> "S" == S Derman <S> writes:

S> This there a way with UNIX to locate a file by inode if you know the
S> inode information?

Yes. Use the find command, like

siwenna% cd /etc/X11/fs
siwenna% ls -li
total 8
142831 -rw-r--r-- 1 root root 1562 Jul 1 08:11 config
109865 -rw-r--r-- 1 root root 1460 Oct 1 2002 config~
siwenna% df
Filesystem Size Used Avail Use% Mounted on
/dev/md0 16G 6.7G 9.1G 43% /
/dev/sda1 699M 41M 658M 6% /boot
siwenna% find / -inum 142831 -print
/etc/X11/fs/config


The catch is, you should give the root of the filesystem as the starting
point, since each filesystem has its own inode numbers.

--
Arto V. Viitanen [email]av@cs.uta.fi[/email]
University of Tampere, Department of Computer and Information Sciences
Tampere, Finland [url]http://www.cs.uta.fi/~av/[/url]

[Martin Blume]

Arto V. Viitanen <av@cs.uta.fi> schrieb

>
> The catch is, you should give the root of the filesystem as the starting
> point, since each filesystem has its own inode numbers.
>

So this means, that given an inode number, a search could return more than
one file, because the same number may be used at the same time in different
filesystems?

Regards
Martin

[Chuck Dillon]

Martin Blume wrote:

> Arto V. Viitanen <av@cs.uta.fi> schrieb
>

>>The catch is, you should give the root of the filesystem as the starting
>>point, since each filesystem has its own inode numbers.
>>

>
> So this means, that given an inode number, a search could return more than
> one file, because the same number may be used at the same time in different
> filesystems?
>

Yes, an inode is filesystem specific so if you search multiple file
systems that inode can be found on any or all of them.

Also, there can be more than one link to the same inode in a file
system so even within a filesystem you can get any number of hits.

-- ced




--
Chuck Dillon
Senior Software Engineer
NimbleGen Systems Inc.

[Juha Laiho]

"Martin Blume" <mblume@socha.net> said:

>Arto V. Viitanen <av@cs.uta.fi> schrieb

>> The catch is, you should give the root of the filesystem as the starting
>> point, since each filesystem has its own inode numbers.
>>

>So this means, that given an inode number, a search could return more than
>one file, because the same number may be used at the same time in different
>filesystems?

It's also possible (and not even rare) for a single inode to have multiple
names. The most common case for this is that every directory inode has
at least two names:
- base/dir
- base/dir/.
(as an example, see "ls -li /etc /etc/.")
.... but this is frequently used for files as well.

Another issue is that an existing and valid inode may have zero names.
These are commonly used as temporary files private to a process:
a process creates the file, and keeps it open while unlinking it.
This'll cause the inode to stay valid, but will lose the last name
pointing from the directory hierarchy to the inode. The inode will be
cleared when the last process holding it open closes it.
--
Wolf a.k.a. Juha Laiho Espoo, Finland
(GC 3.0) GIT d- s+: a C++ ULSH++++$ P++@ L+++ E- W+$@ N++ !K w !O !M V
PS(+) PE Y+ PGP(+) t- 5 !X R !tv b+ !DI D G e+ h---- r+++ y++++
"...cancel my subscription to the resurrection!" (Jim Morrison)

[Barry Margolin]

In article <webmaster-C69BD6.12595611072003@news.telus.net>,
S Derman <webmaster@derman.com> wrote:

>Sorry, I was wondering if there was a system calls that would locate a
>file by inode number.
>
>Similar to open(path name,...), I'd like to open(inode num,...).

No. Two reasons:

1) You would also need to supply the filesystem ID, since an inode number
is only unique within a filesystem.

2) It would allow you to get around directory permissions. Execute
permission on a directory controls whether you can open any files named
within it. If you could go directly to the file without specifying the
pathname, it wouldn't be able to check this.

--
Barry Margolin, [email]barry.margolin@level3.com[/email]
Level(3), Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
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