1guestfs-ruby(3) Virtualization Support guestfs-ruby(3)
2
6 guestfs-ruby - How to use libguestfs from Ruby
7
9 require 'guestfs'
10 g = Guestfs::Guestfs.new()
11 g.add_drive_opts("disk.img",
12 :readonly => 1, :format => "raw")
13 g.launch()
14
16 This manual page documents how to call libguestfs from the Ruby
17 programming language. This page just documents the differences from
18 the C API and gives some examples. If you are not familiar with using
19 libguestfs, you also need to read guestfs(3).
20 EXCEPTIONS
22 Errors from libguestfs functions are mapped into the "Error" exception.
23 This has a single parameter which is the error message (a string).
24
26 # Example showing how to create a disk image.
27 require 'guestfs'
29 output = "disk.img"
31 g = Guestfs::Guestfs.new()
33 # Create a raw-format sparse disk image, 512 MB in size.
35 File.open(output, "w") {
36 |f| f.truncate(512 * 1024 * 1024)
37 }
38 # Set the trace flag so that we can see each libguestfs call.
40 g.set_trace(1)
41 # Attach the disk image to libguestfs.
43 g.add_drive_opts(output, :format => "raw")
44 # Run the libguestfs back-end.
46 g.launch();
47 # Get the list of devices. Because we only added one drive
49 # above, we expect that this list should contain a single
50 # element.
51 devices = g.list_devices()
52 if devices.length != 1 then
53 raise "error: expected a single device from list-devices"
54 end
55 # Partition the disk as one single MBR partition.
57 g.part_disk(devices[0], "mbr")
58 # Get the list of partitions. We expect a single element, which
60 # is the partition we have just created.
61 partitions = g.list_partitions()
62 if partitions.length != 1 then
63 raise "error: expected a single partition from list-partitions"
64 end
65 # Create a filesystem on the partition.
67 g.mkfs("ext4", partitions[0])
68 # Now mount the filesystem so that we can add files.
70 g.mount(partitions[0], "/")
71 # Create some files and directories.
73 g.touch("/empty")
74 message = "Hello, world\n"
75 g.write("/hello", message)
76 g.mkdir("/foo")
77 # This one uploads the local file /etc/resolv.conf into
79 # the disk image.
80 g.upload("/etc/resolv.conf", "/foo/resolv.conf")
81 # Because we wrote to the disk and we want to detect write
83 # errors, call g.shutdown. You don't need to do this:
84 # g.close will do it implicitly.
85 g.shutdown()
86 # Note also that handles are automatically closed if they are
88 # reaped by the garbage collector. You only need to call close
89 # if you want to close the handle right away.
90 g.close()
91
93 # Example showing how to inspect a virtual machine disk.
94 require 'guestfs'
96 if ARGV.length == 0
98 puts "usage: inspect_vm disk.img"
99 exit 1
100 end
101 disk = ARGV[0]
102 g = Guestfs::Guestfs.new()
104 # Attach the disk image read-only to libguestfs.
106 g.add_drive_opts(disk, :readonly => 1)
107 # Run the libguestfs back-end.
109 g.launch()
110 # Ask libguestfs to inspect for operating systems.
112 roots = g.inspect_os()
113 if roots.length == 0
114 puts "inspect_vm: no operating systems found"
115 exit 1
116 end
117 for root in roots do
119 printf("Root device: %s\n", root)
120 # Print basic information about the operating system.
122 printf(" Product name: %s\n", g.inspect_get_product_name(root))
123 printf(" Version: %d.%d\n",
124 g.inspect_get_major_version(root),
125 g.inspect_get_minor_version(root))
126 printf(" Type: %s\n", g.inspect_get_type(root))
127 printf(" Distro: %s\n", g.inspect_get_distro(root))
128 # Mount up the disks, like guestfish -i.
130 #
131 # Sort keys by length, shortest first, so that we end up
132 # mounting the filesystems in the correct order.
133 mps = g.inspect_get_mountpoints(root)
134 mps = mps.sort {|a,b| a[0].length <=> b[0].length}
135 for mp in mps do
136 begin
137 g.mount_ro(mp[1], mp[0])
138 rescue Guestfs::Error => msg
139 printf("%s (ignored)\n", msg)
140 end
141 end
142 # If /etc/issue.net file exists, print up to 3 lines.
144 filename = "/etc/issue.net"
145 if g.is_file filename then
146 printf("--- %s ---\n", filename)
147 lines = g.head_n(3, filename)
148 for line in lines do
149 puts line
150 end
151 end
152 # Unmount everything.
154 g.umount_all()
155 end
156
158 guestfs(3), guestfs-examples(3), guestfs-erlang(3), guestfs-java(3),
159 guestfs-lua(3), guestfs-ocaml(3), guestfs-perl(3), guestfs-python(3),
160 guestfs-recipes(1), http://libguestfs.org/.
161
163 Richard W.M. Jones ("rjones at redhat dot com")
164
166 Copyright (C) 2010-2012 Red Hat Inc.
167
169 This manual page contains examples which we hope you will use in your
170 programs. The examples may be freely copied, modified and distributed
171 for any purpose without any restrictions.
172
174 To get a list of bugs against libguestfs, use this link:
175 https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
176 To report a new bug against libguestfs, use this link:
178 https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
179 When reporting a bug, please supply:
181 · The version of libguestfs.
183 · Where you got libguestfs (eg. which Linux distro, compiled from
185 source, etc)
186 · Describe the bug accurately and give a way to reproduce it.
188 · Run libguestfs-test-tool(1) and paste the complete, unedited output
190 into the bug report.
191libguestfs-1.20.11 2013-08-27 guestfs-ruby(3)