How do I issue a sysrq on a libvirt/kvm guest using "virsh send-key"?

Issue the following from the host:

# virsh send-key <guest_domain_name> KEY_LEFTALT KEY_SYSRQ KEY_<SYSRQ>

Where:

• <SYSRQ> is the capitalized sysrq you would like to issue
• <guest_domain_name> is the name of the guest

For example, to collect a thread dump (sysrq-t) from a guest named rhel5vm, run:

# virsh send-key rhel5vm KEY_LEFTALT KEY_SYSRQ KEY_T

Socket programming in python

TCP/IP Server
---------------------------------------------------------------------------
import socket
import sys
from thread import *

HOST = '' # Symbolic name meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print 'Socket created'

#Bind socket to local host and port
try:
s.bind((HOST, PORT))
except socket.error , msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()

print 'Socket bind complete'

#Start listening on socket
s.listen(10)
print 'Socket now listening'

#Function for handling connections. This will be used to create threads
def clientthread(conn):
#Sending message to connected client
conn.send('Welcome to the server. Type something and hit enter\n')#send only takes string

#infinite loop so that function do not terminate and thread do not end.
while True:

#Receiving from client
data = conn.recv(1024)
reply = 'OK...' + data
if not data:
break
conn.sendall(reply)
#came out of loop
conn.close()

#now keep talking with the client
while 1:
#wait to accept a connection - blocking call
conn, addr = s.accept()
print 'Connected with ' + addr[0] + ':' + str(addr[1])

#start new thread takes 1st argument as a function name to be run, second is the tuple of arguments to the function.
start_new_thread(clientthread ,(conn,))
s.close()

TCP/IP Client
---------------------------------------------------------------------------
import socket #for sockets
import sys #for exit

#create an INET, STREAMing socket
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error:
print 'Failed to create socket'
sys.exit()

print 'Socket Created'

host = 'www.google.com';
port = 80;

try:
remote_ip = socket.gethostbyname( host )

except socket.gaierror:
#could not resolve
print 'Hostname could not be resolved. Exiting'
sys.exit()

#Connect to remote server
s.connect((remote_ip , port))

print 'Socket Connected to ' + host + ' on ip ' + remote_ip

#Send some data to remote server
message = "GET / HTTP/1.1\r\n\r\n"

try :
#Set the whole string
s.sendall(message)
except socket.error:
#Send failed
print 'Send failed'
sys.exit()

print 'Message send successfully'

#Now receive data
reply = s.recv(4096)

print reply

import socket #for sockets
import sys #for exit
try:
#create an AF_INET, STREAM socket (TCP)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error, msg:
print 'Failed to create socket. Error code: ' + str(msg[0]) + ' , Error message : ' + msg[1]
sys.exit();

print 'Socket Created'

host = 'www.google.com'
port = 80

try:
remote_ip = socket.gethostbyname( host )

except socket.gaierror:
#could not resolve
print 'Hostname could not be resolved. Exiting'
sys.exit()

print 'Ip address of ' + host + ' is ' + remote_ip

#Connect to remote server
s.connect((remote_ip , port))

print 'Socket Connected to ' + host + ' on ip ' + remote_ip

#Send some data to remote server
message = "GET / HTTP/1.1\r\n\r\n"

try :
#Set the whole string
s.sendall(message)
except socket.error:
#Send failed
print 'Send failed'
sys.exit()
print 'Message send successfully'

UDP Server
---------------------------------------------------------------------------
import socket
import sys

HOST = '' # Symbolic name meaning all available interfaces
PORT = 8888 # Arbitrary non-privileged port

# Datagram (udp) socket
try :
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
print 'Socket created'
except socket.error, msg :
print 'Failed to create socket. Error Code : ' + str(msg[0]) + ' Message '+ msg[1]
sys.exit()

# Bind socket to local host and port
try:
s.bind((HOST, PORT))
except socket.error , msg:
print 'Bind failed. Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()

print 'Socket bind complete'

#now keep talking with the client
while 1:
# receive data from client (data, addr)
d = s.recvfrom(1024)
data = d[0]
addr = d[1]

if not data:
break

reply = 'OK...' + data

s.sendto(reply , addr)
print 'Message[' + addr[0] + ':' + str(addr[1]) + '] - ' + data.strip()

s.close()

UDP Client
---------------------------------------------------------------------------
import socket #for sockets
import sys #for exit

# create dgram udp socket
try:
s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
except socket.error:
print 'Failed to create socket'
sys.exit()

host = 'localhost';
port = 8888;

while(1) :
msg = raw_input('Enter message to send : ')

try :
#Set the whole string
s.sendto(msg, (host, port))

# receive data from client (data, addr)
d = s.recvfrom(1024)
reply = d[0]
addr = d[1]

print 'Server reply : ' + reply

except socket.error, msg:
print 'Error Code : ' + str(msg[0]) + ' Message ' + msg[1]
sys.exit()