guestfs-perl(3) Virtualization Support guestfs-perl(3)NAMEguestfs-perl - How to use libguestfs from Perl
SYNOPSIS
use Sys::Guestfs;
my $g = Sys::Guestfs->new ();
$g->add_drive_opts ('guest.img', format => 'raw');
$g->launch ();
$g->mount_options ('', '/dev/sda1', '/');
$g->touch ('/hello');
$g->shutdown ();
$g->close ();
DESCRIPTION
This manual page documents how to call libguestfs from the Perl
programming language. This page just documents the differences from
the C API and gives some examples. If you are not familiar with using
libguestfs, you also need to read guestfs(3). To read the full Perl
API, see Sys::Guestfs(3).
ERRORS
Errors from libguestfs functions turn into calls to "croak" (see
Carp(3)).
EXAMPLE 1: CREATE A DISK IMAGE
#!/usr/bin/perl -w
# Example showing how to create a disk image.
use strict;
use Sys::Guestfs;
my $output = "disk.img";
my $g = new Sys::Guestfs ();
# Create a raw-format sparse disk image, 512 MB in size.
open FILE, ">$output" or die "$output: $!";
truncate FILE, 512 * 1024 * 1024 or die "$output: truncate: $!";
close FILE or die "$output: $!";
# Set the trace flag so that we can see each libguestfs call.
$g->set_trace (1);
# Attach the disk image to libguestfs.
$g->add_drive_opts ($output, format => "raw", readonly => 0);
# Run the libguestfs back-end.
$g->launch ();
# Get the list of devices. Because we only added one drive
# above, we expect that this list should contain a single
# element.
my @devices = $g->list_devices ();
if (@devices != 1) {
die "error: expected a single device from list-devices";
}
# Partition the disk as one single MBR partition.
$g->part_disk ($devices[0], "mbr");
# Get the list of partitions. We expect a single element, which
# is the partition we have just created.
my @partitions = $g->list_partitions ();
if (@partitions != 1) {
die "error: expected a single partition from list-partitions";
}
# Create a filesystem on the partition.
$g->mkfs ("ext4", $partitions[0]);
# Now mount the filesystem so that we can add files.
$g->mount_options ("", $partitions[0], "/");
# Create some files and directories.
$g->touch ("/empty");
my $message = "Hello, world\n";
$g->write ("/hello", $message);
$g->mkdir ("/foo");
# This one uploads the local file /etc/resolv.conf into
# the disk image.
$g->upload ("/etc/resolv.conf", "/foo/resolv.conf");
# Because we wrote to the disk and we want to detect write
# errors, call $g->shutdown. You don't need to do this:
# $g->close will do it implicitly.
$g->shutdown ();
# Note also that handles are automatically closed if they are
# reaped by reference counting. You only need to call close
# if you want to close the handle right away.
$g->close ();
EXAMPLE 2: INSPECT A VIRTUAL MACHINE DISK IMAGE
#!/usr/bin/perl -w
# Example showing how to inspect a virtual machine disk.
use strict;
use Sys::Guestfs;
if (@ARGV < 1) {
die "usage: inspect_vm disk.img"
}
my $disk = $ARGV[0];
my $g = new Sys::Guestfs ();
# Attach the disk image read-only to libguestfs.
# You could also add an optional format => ... argument here. This is
# advisable since automatic format detection is insecure.
$g->add_drive_opts ($disk, readonly => 1);
# Run the libguestfs back-end.
$g->launch ();
# Ask libguestfs to inspect for operating systems.
my @roots = $g->inspect_os ();
if (@roots == 0) {
die "inspect_vm: no operating systems found";
}
for my $root (@roots) {
printf "Root device: %s\n", $root;
# Print basic information about the operating system.
printf " Product name: %s\n", $g->inspect_get_product_name ($root);
printf " Version: %d.%d\n",
$g->inspect_get_major_version ($root),
$g->inspect_get_minor_version ($root);
printf " Type: %s\n", $g->inspect_get_type ($root);
printf " Distro: %s\n", $g->inspect_get_distro ($root);
# Mount up the disks, like guestfish -i.
#
# Sort keys by length, shortest first, so that we end up
# mounting the filesystems in the correct order.
my %mps = $g->inspect_get_mountpoints ($root);
my @mps = sort { length $a <=> length $b } (keys %mps);
for my $mp (@mps) {
eval { $g->mount_ro ($mps{$mp}, $mp) };
if ($@) {
print "$@ (ignored)\n"
}
}
# If /etc/issue.net file exists, print up to 3 lines.
my $filename = "/etc/issue.net";
if ($g->is_file ($filename)) {
printf "--- %s ---\n", $filename;
my @lines = $g->head_n (3, $filename);
print "$_\n" foreach @lines;
}
# Unmount everything.
$g->umount_all ()
}
SEE ALSOSys::Guestfs(3), guestfs(3), guestfs-examples(3), guestfs-erlang(3),
guestfs-java(3), guestfs-ocaml(3), guestfs-python(3),
guestfs-recipes(1), guestfs-ruby(3), http://libguestfs.org/.
AUTHORS
Richard W.M. Jones ("rjones at redhat dot com")
COPYRIGHT
Copyright (C) 2011-2012 Red Hat Inc.
LICENSE
This manual page contains examples which we hope you will use in your
programs. The examples may be freely copied, modified and distributed
for any purpose without any restrictions.
BUGS
To get a list of bugs against libguestfs, use this link:
https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
To report a new bug against libguestfs, use this link:
https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
When reporting a bug, please supply:
· The version of libguestfs.
· Where you got libguestfs (eg. which Linux distro, compiled from
source, etc)
· Describe the bug accurately and give a way to reproduce it.
· Run libguestfs-test-tool(1) and paste the complete, unedited output
into the bug report.
libguestfs-1.16.34 2012-11-22 guestfs-perl(3)
