1guestfs-ruby(3)             Virtualization Support             guestfs-ruby(3)
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3
4

NAME

6       guestfs-ruby - How to use libguestfs from Ruby
7

SYNOPSIS

9        require 'guestfs'
10        g = Guestfs::Guestfs.new()
11        g.add_drive_opts("disk.img",
12                         :readonly => true, :format => "raw")
13        g.launch()
14

DESCRIPTION

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
21   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

EXAMPLE 1: CREATE A DISK IMAGE

26        # Example showing how to create a disk image.
27
28        require 'guestfs'
29
30        output = "disk.img"
31
32        g = Guestfs::Guestfs.new()
33
34        # Create a raw-format sparse disk image, 512 MB in size.
35        g.disk_create (output, "raw", 512 * 1024 * 1024)
36
37        # Set the trace flag so that we can see each libguestfs call.
38        g.set_trace(1)
39
40        # Attach the disk image to libguestfs.
41        g.add_drive_opts(output, :format => "raw")
42
43        # Run the libguestfs back-end.
44        g.launch();
45
46        # Get the list of devices.  Because we only added one drive
47        # above, we expect that this list should contain a single
48        # element.
49        devices = g.list_devices()
50        if devices.length != 1 then
51          raise "error: expected a single device from list-devices"
52        end
53
54        # Partition the disk as one single MBR partition.
55        g.part_disk(devices[0], "mbr")
56
57        # Get the list of partitions.  We expect a single element, which
58        # is the partition we have just created.
59        partitions = g.list_partitions()
60        if partitions.length != 1 then
61          raise "error: expected a single partition from list-partitions"
62        end
63
64        # Create a filesystem on the partition.
65        g.mkfs("ext4", partitions[0])
66
67        # Now mount the filesystem so that we can add files.
68        g.mount(partitions[0], "/")
69
70        # Create some files and directories.
71        g.touch("/empty")
72        message = "Hello, world\n"
73        g.write("/hello", message)
74        g.mkdir("/foo")
75
76        # This one uploads the local file /etc/resolv.conf into
77        # the disk image.
78        g.upload("/etc/resolv.conf", "/foo/resolv.conf")
79
80        # Because we wrote to the disk and we want to detect write
81        # errors, call g.shutdown.  You don't need to do this:
82        # g.close will do it implicitly.
83        g.shutdown()
84
85        # Note also that handles are automatically closed if they are
86        # reaped by the garbage collector.  You only need to call close
87        # if you want to close the handle right away.
88        g.close()
89

EXAMPLE 2: INSPECT A VIRTUAL MACHINE DISK IMAGE

91        # Example showing how to inspect a virtual machine disk.
92
93        require 'guestfs'
94
95        if ARGV.length == 0
96          puts "usage: inspect_vm disk.img"
97          exit 1
98        end
99        disk = ARGV[0]
100
101        g = Guestfs::Guestfs.new()
102
103        # Attach the disk image read-only to libguestfs.
104        g.add_drive_opts(disk, :readonly => true)
105
106        # Run the libguestfs back-end.
107        g.launch()
108
109        # Ask libguestfs to inspect for operating systems.
110        roots = g.inspect_os()
111        if roots.length == 0
112          puts "inspect_vm: no operating systems found"
113          exit 1
114        end
115
116        for root in roots do
117          printf("Root device: %s\n", root)
118
119          # Print basic information about the operating system.
120          printf("  Product name: %s\n", g.inspect_get_product_name(root))
121          printf("  Version:      %d.%d\n",
122                 g.inspect_get_major_version(root),
123                 g.inspect_get_minor_version(root))
124          printf("  Type:         %s\n", g.inspect_get_type(root))
125          printf("  Distro:       %s\n", g.inspect_get_distro(root))
126
127          # Mount up the disks, like guestfish -i.
128          #
129          # Sort keys by length, shortest first, so that we end up
130          # mounting the filesystems in the correct order.
131          mps = g.inspect_get_mountpoints(root)
132          mps = mps.sort {|a,b| a[0].length <=> b[0].length}
133          for mp in mps do
134            begin
135              g.mount_ro(mp[1], mp[0])
136            rescue Guestfs::Error => msg
137              printf("%s (ignored)\n", msg)
138            end
139          end
140
141          # If /etc/issue.net file exists, print up to 3 lines.
142          filename = "/etc/issue.net"
143          if g.is_file filename then
144            printf("--- %s ---\n", filename)
145            lines = g.head_n(3, filename)
146            for line in lines do
147              puts line
148            end
149          end
150
151          # Unmount everything.
152          g.umount_all()
153        end
154

SEE ALSO

156       guestfs(3), guestfs-examples(3), guestfs-erlang(3), guestfs-gobject(3),
157       guestfs-golang(3), guestfs-java(3), guestfs-lua(3), guestfs-ocaml(3),
158       guestfs-perl(3), guestfs-python(3), guestfs-recipes(1),
159       http://libguestfs.org/.
160

AUTHORS

162       Richard W.M. Jones ("rjones at redhat dot com")
163
165       Copyright (C) 2010-2012 Red Hat Inc.
166

LICENSE

168       This manual page contains examples which we hope you will use in your
169       programs.  The examples may be freely copied, modified and distributed
170       for any purpose without any restrictions.
171

BUGS

173       To get a list of bugs against libguestfs, use this link:
174       https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
175
176       To report a new bug against libguestfs, use this link:
177       https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
178
179       When reporting a bug, please supply:
180
181       •   The version of libguestfs.
182
183       •   Where you got libguestfs (eg. which Linux distro, compiled from
184           source, etc)
185
186       •   Describe the bug accurately and give a way to reproduce it.
187
188       •   Run libguestfs-test-tool(1) and paste the complete, unedited output
189           into the bug report.
190
191
192
193libguestfs-1.46.0                 2021-09-23                   guestfs-ruby(3)
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