Add a script to arbitrarily change channels on image

scripts/image_signing/set_channel.sh

+#!/bin/bash
+
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Changes the channel on a Chrome OS image.
+
+# Load common constants and variables.
+. "$(dirname "$0")/common.sh"
+
+set -e
+
+if [ $# -ne 3 ]; then
+  cat <<EOF
+Usage: $PROG <image.bin> <from_channel> <to_channel>

[scottz-goog, 2011/04/08 19:18:12]

Why do we need to know the from channel? Do we really care?

[gauravsh, 2011/04/08 19:24:51]

Mainly because of the way it does the change.

+
+<image.bin>: Path to image.
+<from_channel>: The current channel of the image.
+<to_channel>: The new channel of the image.
+EOF
+  exit 1
+fi
+
+main() {
+  local image=$1
+  local from=$2
+  local to=$3
+  
+  rootfs=$(make_temp_dir)
+  mount_image_partition "${image}" 3 "${rootfs}"
+  sed -i "s/\b${from}\b/${to}/" "${rootfs}/etc/lsb-release" &&

[scottz-goog, 2011/04/08 19:18:12]

am I missing something? Why aren't we just calling set_lsb_release.sh IMAGE
CHROMEOS_RELEASE_TRACK $channel?

Or if you want to directly operate on the file.

sed  "s/\(CHROMEOS_RELEASE_TRACK=\).*/\1$channel/" ?
 

[gauravsh, 2011/04/08 19:24:51]

Because the channel also appears in CHROMEOS_RELEASE_DESCRIPTION. I could parse
that separately too - but this seems much more simple and sufficient for our
needs now.

+    echo "Channel change successful."
+
+  cat "$rootfs/etc/lsb-release"
+}
+
+main "$@"