[Libguestfs] How to get information about the guest filesystems by libguestfs

[Richard W.M. Jones]

On Wed, Aug 05, 2009 at 03:30:07PM +0800, Zhang Qian wrote:
> Or I can call guestfs_list_partitions() and guestfs_lvs() to list all
> partitions and logic volumes in guest disk images, and for each of
> them call guestfs_exists() to check if the file I want exist, then
> modify the file.

Right.

Guest filesystem detection is non-trivial with many corner cases,
which is why we didn't write it in C, but wrote a higher level Perl
library to do it:

http://git.et.redhat.com/?p=libguestfs.git;a=blob;f=perl/lib/Sys/Guestfs/Lib.pm;hb=HEAD

However you don't need to use this library, or Perl, directly.  You
can use virt-inspector to get an XML representation of the guest and
mountpoints.

http://libguestfs.org/virt-inspector.1.html

The example below is using a CentOS 5.3 virtual machine.  Note the
<mountpoints> section in the XML:

$ virt-inspector --xml CentOS5x32.img
<operatingsystems>
  <operatingsystem>
    <name>linux</name>
    <distro>centos</distro>
    <arch>i386</arch>
    <major_version>5</major_version>
    <minor_version>3</minor_version>
    <package_format>rpm</package_format>
    <package_management>yum</package_management>
    <root>/dev/VolGroup00/LogVol00</root>
    <mountpoints>
      <mountpoint dev="/dev/VolGroup00/LogVol00">/</mountpoint>
      <mountpoint dev="/dev/sda1">/boot</mountpoint>
      <mountpoint dev="/dev/VolGroup00/LogVol01">swap</mountpoint>
    </mountpoints>
    <filesystems>
      <filesystem dev="/dev/VolGroup00/LogVol00">
        <label></label>
        <uuid>12f2fd13-ac90-4563-a097-391663a17005</uuid>
        <type>ext3</type>
        <content>linux-root</content>
        <spec>/dev/VolGroup00/LogVol00</spec>
      </filesystem>
      <filesystem dev="/dev/VolGroup00/LogVol01">
        <type>swap</type>
        <spec>/dev/VolGroup00/LogVol01</spec>
      </filesystem>
      <filesystem dev="/dev/sda1">
        <label>/boot</label>
        <uuid>18962ebf-6b17-4380-a179-48f1f6a7d973</uuid>
        <type>ext3</type>
        <content>linux-grub</content>
        <spec>LABEL=/boot</spec>
      </filesystem>
    </filesystems>
[lots of other stuff omitted]

Rich.

-- 
Richard Jones, Emerging Technologies, Red Hat  http://et.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://et.redhat.com/~rjones/libguestfs/
See what it can do: http://et.redhat.com/~rjones/libguestfs/recipes.html