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Re: How to Determine If A File Is On NFS? Local? Etc?
by Fletch (Bishop) on Sep 21, 2004 at 14:13 UTC
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This is really something that's not easily made platform independent. If you can limit yourself to a single OS you might can find some pattern to the dev_t numbers (negative for NFS apparently doesn't hold on your platform). One way which only depends on a single external command would be:
- parse the output from df to build a list of filesystems and their type
- for each filesystem save off the dev_t value from (stat( "$mountpoint/." ))[0]
- compare (stat( $file_in_question ))[0] to your saved dev_t list
More of a long shot would be to use Inline::C to get a version of the major()/minor() macros (or hand-roll them), and then compare those against disk device files in /dev. If there's one with the same major/minor, it's a local file; if not it's probably remote (but then you probably wouldn't be able to figure out NFS vs SMB vs . . .).
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[d/l]
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Perhaps someone whould mutter on p5p about having new -X tests to get the major/minor numbers for a device.
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Re: How to Determine If A File Is On NFS? Local? Etc?
by borisz (Canon) on Sep 21, 2004 at 13:27 UTC
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my $d = (stat($filename))[0];
if ( $d < 0 ) {
print "$filename is nfs file\n";
}
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Looking at the first element returned by stat() doesn't seem to work. I tried:
my $nfs_file = '/auto/somewhere/testfile.txt';
my $local_file = '/tmp/testfile.txt';
my @stat_stuff = stat("$nfs_file");
print "Device for nfs file is $stuff[0].";
@stat_stuff = stat("$local_file");
print "Device for local file is $stuff[0].\n";
When I ran it, I got 14 for the NFS mounted file and 10 for the local file. Both greater than 0. Have I misunderstood something? | [reply]
[d/l] |
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This method depends on the way devices are numbered in your
OS. All it means is that you're using an OS which does
not list NFS as a negative device number.
No big deal, just adapt the code to fit.
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Hmm, no that was what borisz wrote. /me goes to read perldoc -f stat.
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Re: How to Determine If A File Is On NFS? Local? Etc?
by jaco (Pilgrim) on Sep 21, 2004 at 16:14 UTC
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I'm not sure if it'll help, but you could consider using something like Filesys::Statfs in combonation with some sort or cwd from the file you're looking for. | [reply] |
Re: How to Determine If A File Is On NFS? Local? Etc?
by radiantmatrix (Parson) on Sep 21, 2004 at 19:33 UTC
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while a good idea it's also very platform specific.
Which it appears is something that he's trying to avoid.
That is to say at least writing the code to deal with the
multiple platforms <is to be avoided.
I don't think there's anyway around this. You're either going
to have to use an exec
(in which case you'll still have very platform specific output) Or code out the values
of the devices based on OS, or some other such nonsense. No matter how you look
at it you're going to have to deal with the fact that OS' don't treat mount points or
device numbers the same way.
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Since he mentioned NFS and Samba, I presumed that platform-specifity wasn't as much an issue as relying on external commands.
I agree that there is pretty much no way of accomplishing the given task reliably in a cross-platform manner. However "an OS with /proc filesystem support" is a much better qualifier than "an OS which has a 'mount' command that produces output in a specific format". So, using the mtab file is still better than using the output from mount.
The closest one could get to "cross-platform" would be checking the most likely OS targets to see which you are running under, and perform the logic that works for that OS. That's an unmaintainable curmudgeon, though.
--
$me = rand($hacker{perl});
All code, unless otherwise noted, is untested
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Re: How to Determine If A File Is On NFS? Local? Etc?
by TedPride (Priest) on Sep 21, 2004 at 19:50 UTC
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Well, if you know what the path of the file is, you should be able to just do:
if (-e $filepath) {
}
Filepaths have to be made with : instead of / on the Mac, though, so you'll need to do an OS test and a $filepath convert if you want this platform independent. | [reply]
[d/l] |
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FWIW, the old Mac OS (9.2.2 or earlier) used ':' as a path delimiter but in Perl on Mac OS X the '/' is used since the OS is based on BSD.
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