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=encoding utf8
=head1 NAME
virt-df - Display free space on virtual filesystems
=head1 SYNOPSIS
virt-df [--options]
virt-df [--options] -d domname
virt-df [--options] -a disk.img [-a disk.img ...]
Old style:
virt-df [--options] domname
virt-df [--options] disk.img [disk.img ...]
=head1 DESCRIPTION
C<virt-df> is a command line tool to display free space on virtual
machine filesystems. Unlike other tools, it doesn't just display the
size of disk allocated to a virtual machine, but can look inside disk
images to see how much space is really being used.
If used without any I<-a> or I<-d> arguments, C<virt-df> checks with
libvirt to get a list of all active and inactive guests, and performs
a C<df>-type operation on each one in turn, printing out the results.
If any I<-a> or I<-d> arguments are specified, C<virt-df> performs a
C<df>-type operation on either the single named libvirt domain, or on
the disk image(s) listed on the command line (which must all belong to
a single VM). In this mode (with arguments), C<virt-df> will I<only
work for a single guest>. If you want to run on multiple guests, then
you have to invoke C<virt-df> multiple times.
Use the I<--csv> option to get a format which can be easily parsed by
other programs. Other options are similar to the standard L<df(1)>
command.
=head1 EXAMPLES
Show disk usage for a single libvirt guest called C<F14x64>. Make the
output human-readable:
# virt-df -d F14x64 -h
Filesystem Size Used Available Use%
F14x64:/dev/sda1 484M 66M 393M 14%
F14x64:/dev/vg_f13x64/lv_root 7.4G 3.4G 4.0G 46%
Show disk usage for a disk image file called C<test.img>:
$ virt-df -a test1.img
Filesystem 1K-blocks Used Available Use%
test1.img:/dev/sda1 99099 1551 92432 2%
=head1 OPTIONS
=over 4
=item B<--help>
Display brief help.
=item B<-a> file
=item B<--add> file
Add I<file> which should be a disk image from a virtual machine. If
the virtual machine has multiple block devices, you must supply all of
them with separate I<-a> options.
The format of the disk image is auto-detected. To override this and
force a particular format use the I<--format=..> option.
=item B<-c> URI
=item B<--connect> URI
If using libvirt, connect to the given I<URI>. If omitted, then we
connect to the default libvirt hypervisor.
If you specify guest block devices directly (I<-a>), then libvirt is
not used at all.
=item B<--csv>
Write out the results in CSV format (comma-separated values). This
format can be imported easily into databases and spreadsheets, but
read L</NOTE ABOUT CSV FORMAT> below.
=item B<-d> guest
=item B<--domain> guest
Add all the disks from the named libvirt guest. Domain UUIDs can be
used instead of names.
=item B<--format=raw|qcow2|..>
=item B<--format>
The default for the I<-a> option is to auto-detect the format of the
disk image. Using this forces the disk format for I<-a> options which
follow on the command line. Using I<--format> with no argument
switches back to auto-detection for subsequent I<-a> options.
For example:
virt-df --format=raw -a disk.img
forces raw format (no auto-detection) for C<disk.img>.
virt-df --format=raw -a disk.img --format -a another.img
forces raw format (no auto-detection) for C<disk.img> and reverts to
auto-detection for C<another.img>.
If you have untrusted raw-format guest disk images, you should use
this option to specify the disk format. This avoids a possible
security problem with malicious guests (CVE-2010-3851).
=item B<-h>
=item B<--human-readable>
Print sizes in human-readable format.
You are not allowed to use I<-h> and I<--csv> at the same time.
=item B<-i>
=item B<--inodes>
Print inodes instead of blocks.
=item B<--one-per-guest>
Run one libguestfs appliance per guest. Normally C<virt-df> will
add the disks from several guests to a single libguestfs appliance.
You might use this option in the following circumstances:
=over 4
=item *
If you think an untrusted guest might actively try to exploit the
libguestfs appliance kernel, then this prevents one guest from
interfering with the stats printed for another guest.
=item *
If the kernel has a bug which stops it from accessing a
filesystem in one guest (see for example RHBZ#635373) then
this allows libguestfs to continue and report stats for further
guests.
=back
=item B<--uuid>
Print UUIDs instead of names. This is useful for following
a guest even when the guest is migrated or renamed, or when
two guests happen to have the same name.
Note that only domains that we fetch from libvirt come with UUIDs.
For disk images, we still print the disk image name even when
this option is specified.
=item B<-v>
=item B<--verbose>
Enable verbose messages for debugging.
=item B<-V>
=item B<--version>
Display version number and exit.
=item B<-x>
Enable tracing of libguestfs API calls.
=back
=head1 STATVFS NUMBERS
C<virt-df> (and L<df(1)>) get information by issuing a L<statvfs(3)>
system call. You can get the same information directly, either from
the host (using libguestfs) or inside the guest:
=over 4
=item From the host
Run this command:
guestfish --ro -d GuestName -i statvfs /
(change C</> to see stats for other filesystems).
=item From inside the guest
Run this command:
python -c 'import os; s = os.statvfs ("/"); print s'
(change C</> to see stats for other filesystems).
=back
=head1 NOTE ABOUT CSV FORMAT
Comma-separated values (CSV) is a deceptive format. It I<seems> like
it should be easy to parse, but it is definitely not easy to parse.
Myth: Just split fields at commas. Reality: This does I<not> work
reliably. This example has two columns:
"foo,bar",baz
Myth: Read the file one line at a time. Reality: This does I<not>
work reliably. This example has one row:
"foo
bar",baz
For shell scripts, use C<csvtool> (L<http://merjis.com/developers/csv>
also packaged in major Linux distributions).
For other languages, use a CSV processing library (eg. C<Text::CSV>
for Perl or Python's built-in csv library).
Most spreadsheets and databases can import CSV directly.
=head1 SHELL QUOTING
Libvirt guest names can contain arbitrary characters, some of which
have meaning to the shell such as C<#> and space. You may need to
quote or escape these characters on the command line. See the shell
manual page L<sh(1)> for details.
=head1 EXIT STATUS
This program returns 0 if successful, or non-zero if there was an
error.
=head1 SEE ALSO
L<df(1)>,
L<guestfs(3)>,
L<guestfish(1)>,
L<virt-filesystems(1)>,
L<http://libguestfs.org/>.
=head1 AUTHOR
Richard W.M. Jones L<http://people.redhat.com/~rjones/>
=head1 COPYRIGHT
Copyright (C) 2009-2012 Red Hat Inc.
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