def install_state(version_tag, machine = E.LOCALHOST, rootdir = "/"):
"""
This function returns the state of the install of version_num
if it exists. Otherwise, it returns null.
"""
filename = "%s/%s/STATE" % (get_top_dir(rootdir), str(version_tag))
output = E.cat([machine], filename)
if output == None:
return None
install_state = string.strip(output)
if install_state not in INSTALL_STATES:
return None
return install_state
