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"Sight" Survey (SS42)
Printer Port Capture in Windows NT and 2000
Windows NT Print Capture is set up and controlled by Windows NT Command-line programs. These are Windows NT programs that do not have a GUI (graphical user interface) and are accessed and run through an NT Command Prompt Window. Although the Command Prompt window is often referred to as the "DOS window" (and has an MSDOS icon), print redirection is not itself a DOS program, but an NT Systems Administration tool. These tools are powerful, and can cause problems if misused: accordingly they should only be used by System Administrators. All the issues discussed here are Windows NT issues. However we have found that the topic of print redirection is so poorly covered in the Windows documentation that we are putting together this paper in self defense! We assume that you are an NT Administrator, generally familiar with how to set up and configure NT, but unfamiliar with this specific topic - redirection. Getting into the more general how and why of administering NT is well beyond the scope of this document - there are numerous courses and books available on the subject. These network control programs are accessed through the NET command, optionally followed by parameters that direct what part of the network setup is to be displayed or changed, and what the desired effect of any changes is. The following is a hands-on tutorial style explanation of print capture. The source material is taken directly from Windows NT 4.0, but as far as I'm aware there is no explanation in the supplied Windows documentation, on-line or printed, that explains the why, what, and how. To use the NET command, first open a Command Prompt window. Type NET /? and press Enter. The resulting dialog is shown below. Commands you type are shown in Courier BOLD. The computer responses are show in Courier only (not bold).
C:\>net /? You will see that one of the options (near the end of the list) is USE. Next, display the somewhat cryptic Help file for the NET USE variation of the command. To do this type: NET HELP USE | MORE and press Enter. The "|" symbol is the vertical bar, sometimes known as "pipe", and usually found as the "shift" option of the "\" (back slash) key. Adding | MORE to the command displays the help one screen at a time.
C:\>net help use |
more devicename Assigns a name to connect to the resource or specifies the device to be disconnected. There are two kinds of devicenames: disk drives (D: through Z:) and printers (LPT1: through LPT3:). Type an asterisk instead of a specific devicename to assign the next available devicename.
\\computername Is the name of the computer controlling the shared resource. If the computername contains blank characters, enclose the double backslash (\\) and the computername in quotation marks (" "). The computername may be from 1 to 15 characters long.
\sharename Is the network name of the shared resource.
\volume Specifies a NetWare volume on the server. You must have Client Services for Netware (Windows NT Workstations) or Gateway Service for Netware (Windows NT Server) installed and running to connect to NetWare servers.
password Is the password needed to access the shared resource.
* Produces a prompt for the password. The password is not displayed when you type it at the password prompt.
/USER Specifies a different username with which the connection is made.
domainname Specifies another domain. If domain is omitted, the current logged on domain is used.
username Specifies the username with which to logon.
/HOME Connects a user to their home directory.
/DELETE Cancels a network connection and removes the connection from the list of persistent connections.
/PERSISTENT Controls the use of persistent network connections. The default is the setting used last.
YES Saves connections as they are made, and restores them at next logon.
NO Does not save the connection being made or subsequent connections; existing connections will be restored at next logon. Use the /DELETE switch to remove persistent connections.
Displays Help one screen at a time. To display the redirections, if any, on your computer use the NET USE command without any parameters, as shown below. The computer responses are for my particular computer (the one I'm writing this on). Yours will certainly be different.
C:\>net use
Status
Local Remote Network The first line of the output tells you that NET USE is currently set to remember changes you make to the configuration. This is usually necessary, as you don't want to make the changes over and over again. Changing this setting is explained below. The output also shows that my computer's H: drive is in fact the C: drive on the computer named \\486-66-A. The "Disconnected" label shows that that computer is not on the network at the moment (it was actually switched off). Similarly my I: drive is the D: drive on that computer. Also shown are my computer's LPT2 and LPT3 ports, both of which are connected to the printer whose "sharename" is "hplaserj" and which is controlled through the computer called "MOON." In this particular case the printer is a Hewlett-Packard PCL3 LaserJet, connected to an Ethernet network through an HP JetDirect box, and the driver was installed (and the print queue managed) by MOON. The OK label shows that last time my computer tried to access LPT2 it was successful (it does not necessarily mean that it's OK right now). In the following, I assume that you do not have a printer physically connected to port LPT2 on your computer. If your computer does not have a printer on LPT2, or does not have an LPT2 port, it will behave like mine. If it does have a printer on LPT2 then setting up LPT2 redirection will route all print output from the local printer to the network printer. Removing redirection will stop this routing and the local printer will work again. Let's try disconnecting port LPT2 from the network printer. To do this we use the command with the /delete option:
C:\>net use
LPT2 /delete Now display the redirections once again, with NET USE:
C:\>net use
Status Local
Remote Network Notice that port LPT2 is no longer re-directed. You can only tell this by noting that LPT2 (like LPT1) does not appear in the redirection list. To set up a redirection (or, in this case, restore one you deleted) use the
command sequence:
C:\>net use
lpt2 \\moon\hplaserj ...and once again, check the results:
C:\>net use
To test whether redirection is successful, use the COPY command to copy from the screen (CON, short for Console) to the printer port (in this case LPT2) as follows:
C:\>copy
con lpt2 The message "1 file(s) copied" means you were successful. Note that ^L means Ctrl-L (press and hold the Ctrl key; press and release the L key; release the Ctrl key), and ^Z means Ctrl-Z. Do not type the ^ character! You should get one sheet of paper with "Mary had a little hippopotamus" printed on it. If redirection is successful, but you get scrambled printing (or none at all), you probably have an inexpensive "Windows Only" printer. These printers are of limited use, and are generally unsuitable for CAD applications. While you are experimenting, you may want to monitor the print queue foe the redirected printer so you can watch what is happening. If redirection is not successful (and you have no local LPT2 print capability) you'll get this message:
Server Name Remark …and to find out the resources available to you on a specific computer, use NET VIEW <computername> like this:
C:\>net use /persistent:no
C:\>net use
...and to turn it back on again:
C:\>net
use /persistent:yes
© 2008 by Carlson Software, Inc. Last modified November 18, 2008
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