Re: test if a subvolume is a snapshot?

[Hugo Mills <hugo@carfax.org.uk>]

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On Fri, Sep 08, 2017 at 04:25:55PM +0100, Tomasz Kłoczko wrote:
> On 8 September 2017 at 14:10, David Sterba <dsterba@suse.cz> wrote:
> > On Fri, Sep 08, 2017 at 10:54:46AM +0200, Ulli Horlacher wrote:
> > > How can I test if a subvolume is a snapshot?
> >
> > The inode number is 256 on a btrfs filesystem:
> >
> > if [ stat -f --format=%T $path = btrfs -a stat --format=%i $path = 256 ]; ...
> 
> This oneliner shows how much really basic btrfs tools commands syntax
> is broken by design :(
> Looking on how so freakishly overcomplicated btrfs command syntax is
> that command like above is completely unintuitive and unreadable

   This is nothing to do with btrfs tooling. The two commands involved
here are test (aka "[") and stat.

> sometimes I'm really thinking about start rewrite btrfs-progs to make
> btrfs basic tools syntax as similar as it is only possible to ZFS zfs,
> zpool and zdb commands on using which in +90% cases you can guess how
> necessary syntax must look like without looking on man pages.
> 
> Any volunteers want to join to help implement something like this?
> Maybe someone already started doing this?

   The main complaint that can be directed at the btrfs command is
that its output is rarely machine-processable. It would therefore make
sense to have a "--table" or "--structured" mode for output, which
would be more trivially parsable by shell tools.

   Hugo.

-- 
Hugo Mills             | Ceci est un travail pour l'Australien.
hugo@... carfax.org.uk |
http://carfax.org.uk/  |
PGP: E2AB1DE4          |                                 Louison, Delicatessen

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