White Paper:
Easy Remote Program Installations Using the
Task Scheduler Service
Rev 4 - April 27, 2006
Lieberman Software Corporation
www.liebsoft.com
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Abstract
In this paper you will see how simple software
installations can be easily accomplished using the built-in Task Scheduler
service already installed in every Windows® NT, 2000 and XP machine.
Contents
1. Introduction
2. Requirements and Methods of Software Distribution
3. Packaged Distribution
4. Remote Execution of the
Installation Package
5.
Other Free Alternatives to the AT Command
6.
Going Further
7.
A Simple Step-up from Scripts
8.
Summary
1. Introduction
The
periodic distribution of new programs, patches and updates represent a large
portion of an administrator’s duties. The challenge is to find the right tool
to do the distribution with a minimum of fuss and muss. It turns out that you
can do a pretty good job at simple software distribution with minimal effort by
just doing remote file copies combined with creating jobs in each remote system
to install the just copied file(s). The rest of the paper will walk you
through the details.
For
really complex installations you have a wealth of options. Products such as
Microsoft’s SMS, HP’s OpenView, Novell’s ZenWorks and IBM’s Tivoli do an
excellent job with even the most complex installations. Just remember that
these tools do take a significant amount of time and money to setup and manage,
but they can do just about anything you can conceive of when it comes to
program installation.
To
push a new software package, the following minimal steps are required:
·
Distributing the package – this is
just copying the file(s) (easy)
·
Remote Execution of the Package –
how do you remotely run the program?
One
of the nice things about administering Windows NT and later operating systems
is that they are chock full of remote management services. In this case, the
distribution of a software package can be done easily since each hard drive
letter is automatically shared out over the network (C$, D$, E$...). Even the
directory used by the operating system has its own share (admin$) that is
available to read/write across the network. This directory sharing (as well as
other management features) is accomplished by the Server service running on
every NT machine.
Copying
to remote destination directories on each machine can be accomplished by either
using the built-in command-line Copy command or the standalone XCOPY.EXE
program (the resource kit Robocopy program is another excellent choice).
Copying is a matter of selecting the source directory/files (usually stored
locally) and then setting the destination path. To handle a destination path
on a remote system, the path must be encoded using UNC (Universal Naming
Convention) in the format:
\\Server\ShareName\DestinationPath
For
the copy operation to succeed, the copy command (or copy program) must be
executed while running under an account that is seen by all target systems as
an administrator. The
common administrator account requirement can be quite a challenge if the
distribution must be done across multiple domains without trusts, or to
multiple workgroups. Another challenge is the handling of off-line machines
via some kind of auto-retry mechanism.
4. Remote Execution of the Installation Package
The
secure remote execution of the installation package is the primary reason most
administrators buy a third party software management package.
A
free secure remote execution agent is already installed in all Microsoft
Windows NT, 2000 and XP machines and it is known as the “Task Scheduler”
service. The Task Scheduler can be remotely controlled to run any program
either immediately or at a specific time and date. It even produces a log of the
success or failure of the remote launch.
The
least expensive way to manage the jobs on remote systems is via the
command-line accessible AT command. To see all of the options of the AT
command, just type:
AT /?
Here
is the output of the command:
The AT command schedules commands and programs to
run on a computer at
a specified time and date. The Schedule service must
be running to use
the AT command.
AT [\\computername] [ [id] [/DELETE] | /DELETE
[/YES]]
AT [\\computername] time [/INTERACTIVE]
[ /EVERY:date[,...] | /NEXT:date[,...]]
"command"
\\computername Specifies a remote computer.
Commands are scheduled on the
local computer if this parameter
is omitted.
id Is an identification number
assigned to a scheduled
command.
/delete Cancels a scheduled command. If
id is omitted, all the
scheduled commands on the
computer are canceled.
/yes Used with cancel all jobs command
when no further
confirmation is desired.
time Specifies the time when command
is to run.
/interactive Allows the job to interact with
the desktop of the user
who is logged on at the time the
job runs.
/every:date[,...] Runs the command on each
specified day(s) of the week or
month. If date is omitted, the
current day of the month
is assumed.
/next:date[,...] Runs the specified command on the
next occurrence of the
day (for example, next
Thursday). If date is omitted, the
current day of the month is
assumed.
"command" Is the Windows NT
command, or batch program to be run.
To
run a just copied installation package, the administrator would issue the
command:
AT
\\SERVER 01:00 “C:\program files\my program\setup.exe
–s:data.inf”
In
this case we would be running the setup.exe program at 1:00 AM in our just
created directory and the installation program would get its installation parameters
from the data.inf file. Of course, each installation program has its own
syntax and method of passing the setup parameters to an installation program.
The
log of the Task Scheduler can be obtained by browsing to each machine,
opening the Scheduled Tasks folder, and then using the menu option:
Advanced | View Log
5. Other Free Alternatives to the AT Command
When
you need to execute a remote installation, there are plenty of other free
programs in the Microsoft Server Resource Kit that perform remote execution.
However, all of the following programs require the installation of a remote
service or the starting of a remote program on each remote system.
The
Remote Command Service consists of the client program: RCMD.EXE and its remote
matching service RCMDSVC.EXE. The RCMDSVC service needs to be copied to every
machine and installed. Remote installation of the service can be accomplished
by the SC (for information, use the command: SC /?) command or en masse to all
machines via Lieberman Software’s Service Account Manager. This program
performs secure authentication before any transactions are allowed. Below is
an example of the Remote Command Service:
The
Remote Command Line consists of a single file: REMOTE.EXE (also in the Server Resource
Kit). This program is not recommended since there is no security provided and
anyone can perform remote commands to any machine where the REMOTE.EXE program
is running. Manual installation and starting is required on all remote
machines.
Another
alternative is the Remote Console utility in the Resource Kit. This utility
operates like a Telnet session in Unix. It is located in the Resource Kit
directory under \RCONSOLE. This program consists of a remote network service
that must be installed manually on every machine, and a remote control called
RCLIENT.EXE. This utility is more suited for a one-by-one remote installation.
Finally,
the TCP/IP Remote Shell Service operates like the Unix Remote Shell Service (rsh).
This is a service-based package also provided in the Server Resource Kit. This
tool installed using the same methods as
the Remote Command Service. Its security depends on the creation of a custom
RHOSTS file that specifies all machines and users that are allowed remote
access via this service.
Using
scripts to drive the copy and AT commands (or remote control programs/services)
allows software installations at virtually zero cost other than your
development time. Some of the goodies you generally miss with scripts include:
·
Easy management of a dynamically
changing machine list
·
No auto-retry of off-line machines
·
Multi-threaded operation for
concurrent installation where speed is important
·
Comprehensive logging of
operations (auditing)
·
Ability to manage the distribution
of more than one package
·
Extensive reporting of
installation status
·
May support impersonation to allow
cross domain/workgroup installation
·
You have to document and maintain
that script you create (not a lot of fun)
A
step up from writing scripts and a step down from using a full blown software
distribution package is the use of a specialized tool to do mass management of
the scheduled tasks on all your remote machines. One such tool is Task
Scheduler Pro from Lieberman Software (http://www.liebsoft.com). Although the product is not a software
distribution product, it has an integrated file copying option included in its
scheduled task management function. By combining task management with built-in
concurrent file copying, the program can be used to quickly install simple
software packages in minutes. The program interfaces are nearly identical to
those in Microsoft’s own tools, except for the addition of the file copying option:
When
this copy button is pressed, the program provides a general purpose file copy
editor:
As
an added bonus, the program can also simultaneously retrieve all of the Task
Scheduler logs from all of your systems for immediate review. It also has
automatic retry, so if any of the target systems are off-line the program will
keep trying to do the installation until it is completed.
Task
Scheduler Pro is fully multithreaded for fast simultaneous operation, logs all
transactions to a permanent text file, and supports unlimited impersonation so
that cross-domain and multiple workgroups are supported without having to log
off and on multiple times.
For
those extremely familiar with the AT command, the account AT uses is normally
hard coded per machine and requires a personal visit to each machine to change
the account. Task Scheduler Pro can display the accounts used by the AT
command on each system and allow you to change them all remotely!
For
complex software installations, full-featured third party packages are the
ideal choice for administrators. For those without a budget, simple scripts
combining copying and the AT command can fit the bill nicely. And finally, for
those that need to do simple installations and don’t have a lot of time to
create scripts, and are looking for more functionality, there is the Task
Scheduler Pro product from Lieberman Software.
Our
support staff is available to answer your technical questions whether you are a
customer or not
|
Lieberman
Software
1900 Ave of the Stars - Suite 425
Los Angeles, CA 90067
Web:
www.liebsoft.com
|
Voice: 800.829.6263
(USA/Canada)
Voice: (01) 310.550.8575
(Worldwide)
Fax: (01) 310.550.1152
(Worldwide)
Email: support@liebsoft.com
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