Turning off services SOLVED

[Ross Boylan <RossBoylan@stanfordalumni.org>]

At various times I have wanted to turn off certain daemons without
uninstalling their packages.  I couldn't find any good way to do this,
so I wrote a little script.  I'm making it available under the GPL.

I've since discovered that the some packages also create a bunch of
crontab jobs, and they are still cluttering things up a bit.

If there's a better way to do this, I'd love to hear it.

#! /usr/bin/python
# switchDemon.py
#
# Usage: switchDemon.py (--on | --off) <list of demon names>
#
# This script will scan, turn off, or turn on selected
# demons in /etc/rc?.d/.  It does so by renaming S* symbolic
# links so the services won't start.
# Scan mode (neither --on nor --off) simply reports the status
# of the demons.
# Note that demons are not actually started or stopped by this script;
# it just controls what will happen at system startup.
#
# (c) 2001 Ross Boylan RossBoylan@stanfordalumni.org
# Made available under the GPL (see www.gnu.org)

import glob, os.path, re, sys

class Demon:
    "Information and actions on a demon"

    gDisabled = "Disabled-"

    def __init__(self, name):
        "Name of demon"
        if not os.path.exists("/etc/init.d/"+name):
            raise name + " is not a known demon"
        self._name = name
        self._statuses = []

    def checkStatus(self):
        "Check status at various run levels"
        self.doOverRunLevels(self._checkStatus)

    def turnOff(self):
        "Make it so won't run at next system start"
        self.doOverRunLevels(self._turnOff)
        self.checkStatus()

    def turnOn(self):
        "We will start on next run level change"
        self.doOverRunLevels(self._turnOn)
        self.checkStatus()        

    def doOverRunLevels(self, method):
        "Invoke method over all run levels"
        for rl in glob.glob("/etc/rc[0-9Ss].d"):
            method(rl, rl[-3])

    def _checkStatus(self, directory, runLevel):
        "See if we are around and fill in _statuses if we are"
        aRegex = re.compile("("+Demon.gDisabled+r")?S(\d\d)"+self._name);
        for file in os.listdir(directory):
            aMatch = aRegex.search(file)
            if aMatch:
                aStatus = DemonStatus(runLevel, aMatch.group(2), not aMatch.group(1))
                self._statuses.append(aStatus)
                return

    def _turnOff(self, directory, runLevel):
        "Disable demon for future reboots"
        aRegex = re.compile(r"S(\d\d)"+self._name)
        for file in os.listdir(directory):
            aMatch = aRegex.match(file)  # must be at start
            if aMatch:
                os.rename(os.path.join(directory, file),
                          os.path.join(directory, Demon.gDisabled+file))
                # no return values documented for os.rename
                return
       
    def _turnOn(self, directory, runLevel):
        "Enable demon for future reboots"
        aRegex = re.compile(Demon.gDisabled+r"S(\d\d)"+self._name)
        for file in os.listdir(directory):
            aMatch = aRegex.match(file)  # must be at start
            if aMatch:
                os.rename(os.path.join(directory, file),
                          os.path.join(directory, file[len(Demon.gDisabled):]))
                # no return values documented for os.rename
                return

    def reportTo(self, file):
        "Send human readable report to stream"
        file.write("Demon %s:\n"%self._name)
        for aStatus in self._statuses:
            file.write("\t%s\n"%str(aStatus))
        

class DemonStatus:
    "Status of a given demon"

    def __init__(self, runlevel, priority, enabled=1):
        "Priority (nn) of demon and whether it is enabled"
        # runlevel is a single 0, 1, ...
        self._runlevel = runlevel
        self._priority = priority
        self._enabled = enabled

    def __str__(self):
        if self._enabled:
            msg = "Enabled"
        else:
            msg = "Turned off"
        return "%s for run level %s (priority %s)"%(msg, self._runlevel, self._priority)

    def isEnabled(self):
        if self._enabled:
            return "on"
        else:
            return "off"


aCommand = sys.argv[1]
if aCommand[0] == "-":
    if aCommand[-1] == "f":
        anAction = "turnOff"
    elif aCommand[-1] == "n":
        anAction = "turnOn"
    else:
        print "Command not understood"
    names = sys.argv[2:]
else:
    anAction = "checkStatus"
    names = sys.argv[1:]
    
for aDemonName in names:
    aDemon = Demon(aDemonName)
    Demon.__dict__[anAction](aDemon)
    aDemon.reportTo(sys.stdout)