Add a simple demonstrative guestfish script. (Original idea - Rich

Jones).

libguestfs/hostname-guest-edit.py

@@ -0,0 +1,81 @@
+#!/usr/bin/python
+#-------------------------------------------------------------
+# Original idea -- Rich Jones<[email protected]> --
+    # -https://rwmj.wordpress.com/2010/08/30/python-script-to-replace-templates-in-configuration-files-in-vms/
+# Modified by  -- Kashyap Chamarthy<[email protected]>
+# PURPOSE: To replace hostname in a guest using guestfish
+# Please read the comments.
+
+# *****WARNING**** : This should not be executed on a LIVE vm
+#-------------------------------------------------------------
+
+
+image = "/var/lib/libvirt/images/rhel6test.qcow2"
+
+#root_filesystem = "/dev/sda4"
+root_filesystem = "/dev/VolGroup/lv_root"
+
+filename = "/etc/sysconfig/network"
+
+pattern = "HOSTNAME=(.*)"
+replacement = "HOSTNAME=rootconf2012.foo.bar.com"
+
+
+# Import some standard python modules
+import tempfile
+import os
+import fileinput
+import shutil
+import sys
+import re
+
+# Import the guestfs module
+import guestfs
+
+
+# Create a libguestfs handle.
+g = guestfs.GuestFS ()
+
+# Add the disk image.
+g.add_drive (image)
+
+# NOTE:the libguestfs handle should be launched *after* adding the
+# drive(s), and *before* any other commands are run. This launches the
+# qemu subprocess.
+g.launch ()
+
+# Set the trace flag so that we can see each libguestfs call
+g.set_trace (1)
+
+# To access the filesystem in the disk image, mount it. (NOTE: both
+# block-devices and LVMs are detected)
+g.mount_options ("", root_filesystem, "/")
+
+#Create a temporary directory to edit the file. 
+tmpdir = tempfile.mkdtemp ()
+tmpfile = os.path.join (tmpdir, "filename")
+
+# Copy the file to a temporary location
+g.download (filename, tmpfile)
+
+# Edit the pattern w/ replacement
+for line in fileinput.FileInput (tmpfile, inplace=1):
+
+    line = re.sub(pattern, replacement, line)
+    print line,
+
+# Upload the file
+g.upload (tmpfile, filename)
+
+# Unmount all the file system(s).
+g.umount_all ()
+
+# This will write any data buffered in memory to disk 
+# NOTE: This is very important to do. 
+g.sync ()
+
+# Remove the temporary directory created.
+shutil.rmtree (tmpdir)
+
+# Exit
+sys.exit(0)