tools/xen-console-wrapper

#!/bin/bash
#

# Copyright (C) 2011 Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

XEN_CMD="$1"
INSTANCE="$2"

unpause() {
  ispaused=$(xm list -l "$INSTANCE" 2>/dev/null |
             sed -n 's/^[[:blank:]]*(state ..\(.\)...)/\1/p')
  [[ "$ispaused" == "p" ]] || return
  # As there is no way to be sure when xm console has actually connected to the
  # instance, sleep for a few seconds before unpausing the instance. This is a
  # tradeoff between missing some console output if the node is overloaded and
  # making the user wait everytime when the node isn't so busy.
  sleep 3
  # Send \r\n after notice as terminal is in raw mode
  printf "Instance $INSTANCE is paused, unpausing\r\n"
  xm unpause "$INSTANCE"
}

unpause &
exec $XEN_CMD console "$INSTANCE"