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


NAME
       guestfs-ruby - How to use libguestfs from Ruby

SYNOPSIS
        require 'guestfs'
        g = Guestfs::Guestfs.new()
        g.add_drive_opts("disk.img",
                         :readonly => true, :format => "raw")
        g.launch()

DESCRIPTION
       This manual page documents how to call libguestfs from the Ruby
       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).

   EXCEPTIONS
       Errors from libguestfs functions are mapped into the "Error" exception.
       This has a single parameter which is the error message (a string).

EXAMPLE 1: CREATE A DISK IMAGE
        # Example showing how to create a disk image.

        require 'guestfs'

        output = "disk.img"

        g = Guestfs::Guestfs.new()

        # Create a raw-format sparse disk image, 512 MB in size.
        g.disk_create (output, "raw", 512 * 1024 * 1024)

        # 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")

        # 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.
        devices = g.list_devices()
        if devices.length != 1 then
          raise "error: expected a single device from list-devices"
        end

        # 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.
        partitions = g.list_partitions()
        if partitions.length != 1 then
          raise "error: expected a single partition from list-partitions"
        end

        # Create a filesystem on the partition.
        g.mkfs("ext4", partitions[0])

        # Now mount the filesystem so that we can add files.
        g.mount(partitions[0], "/")

        # Create some files and directories.
        g.touch("/empty")
        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 the garbage collector.  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
        # Example showing how to inspect a virtual machine disk.

        require 'guestfs'

        if ARGV.length == 0
          puts "usage: inspect_vm disk.img"
          exit 1
        end
        disk = ARGV[0]

        g = Guestfs::Guestfs.new()

        # Attach the disk image read-only to libguestfs.
        g.add_drive_opts(disk, :readonly => true)

        # Run the libguestfs back-end.
        g.launch()

        # Ask libguestfs to inspect for operating systems.
        roots = g.inspect_os()
        if roots.length == 0
          puts "inspect_vm: no operating systems found"
          exit 1
        end

        for root in roots do
          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.
          mps = g.inspect_get_mountpoints(root)
          mps = mps.sort {|a,b| a[0].length <=> b[0].length}
          for mp in mps do
            begin
              g.mount_ro(mp[1], mp[0])
            rescue Guestfs::Error => msg
              printf("%s (ignored)\n", msg)
            end
          end

          # If /etc/issue.net file exists, print up to 3 lines.
          filename = "/etc/issue.net"
          if g.is_file filename then
            printf("--- %s ---\n", filename)
            lines = g.head_n(3, filename)
            for line in lines do
              puts line
            end
          end

          # Unmount everything.
          g.umount_all()
        end

SEE ALSO
       guestfs(3), guestfs-examples(3), guestfs-erlang(3), guestfs-gobject(3),
       guestfs-golang(3), guestfs-java(3), guestfs-lua(3), guestfs-ocaml(3),
       guestfs-perl(3), guestfs-python(3), guestfs-recipes(1),
       http://libguestfs.org/.

AUTHORS
       Richard W.M. Jones ("rjones at redhat dot com")

COPYRIGHT
       Copyright (C) 2010-2023 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:

       o   The version of libguestfs.

       o   Where you got libguestfs (eg. which Linux distro, compiled from
           source, etc)

       o   Describe the bug accurately and give a way to reproduce it.

       o   Run libguestfs-test-tool(1) and paste the complete, unedited output
           into the bug report.

libguestfs-1.52.0                 2024-01-05                   guestfs-ruby(3)