Re: [libvirt] [PATCHv4 1/2] virsh: add new --details option to pool-list
On Tue, Jun 22, 2010 at 12:35:32PM -0600, Eric Blake wrote:
On 06/22/2010 12:24 PM, Hugh O. Brock wrote:
>> Correct, we shouldn't change this behaviour - it'll break apps parsing
>> the output
>
> FWIW Rich Jones complains that the output as it stands is nigh on
> unparseable anyway. Perhaps we should consider that a bug, and fix
> it...
The new --details option is our chance to change output - it outputs
whatever format we want, because it is a new flag; Rich, do you have any
preferences about what it _should_ output?
Here's what pool-list --details would currently do, if we applied
Justin's patch as-is (modulo no line wrapping added by my email client):
Sorry, been away for a couple of weeks.
virsh # pool-list --details --all
Name State Autostart Persistent Capacity Allocation Available
---------------------------------------------------------------------------
default running yes yes 1.79 TB 1.49 TB 304.77 GB
image_dir running yes yes 1.79 TB 1.49 TB 304.77 GB
tmp inactive no yes - - -
One good thing, and several bad things about that. The good thing is
that empty columns are presented with '-' which means you can use awk
and sort -k to parse the output columnwise.
The bad things:
* Space within fields "1.79 TB" (awk / sort -k in fact _won't_ work).
* Numeric fields aren't numbers: You can't sort -n on "1.79 TB", and
you can't read that number into a script and do math on it. Most
tools have a "-h" or "--human" option in order to generate human-
readable numbers (without spaces), but default to just printing the
raw numbers.
* Unnecessary "-------" line.
* Title line should be optional. Have a --no-title option or
something like that to suppress it.
* Does virsh still print an unnecessary blank line after the output?
If so, stop doing that.
Rich.
--
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