Windows/Linux Integration Tips
Windows Tips
Linux Tips
General Computing Tips
OK, if you use Windows 2000 and print to a Red Hat 7.3 Samba server,
you've undoubtedly gotten that annoying "Access denied: Unable to connect"
message. What's causing that is a missing parameter in the Samba
configuration file, that tells Windows 2000 to properly treat the
printer as a remote device and not locally attached. To fix this,
change the [printers] section of /etc/samba/smb.conf to:
[printers]
comment = All Printers
path = /var/spool/samba
browseable = no
# Set public = yes to allow user 'guest account' to print
guest ok = yes
writable = yes
printable = yes
use client driver = yes
The important parameter is the last one. The other changes from the
default Red Hat configuration might be irrelevant, but I haven't tested
them, and this just works :-)
But Wait, There's More!
So you can connect, but now your print jobs never finish because
they're always paused, right? Wrong! The printing daemon is doing
something stupid, not deleting finished print jobs from the queue. Why
this is default is anybody's guess. To fix this, add these lines to
/etc/lpd.conf:
stalled_time=300
done_jobs=0
The first parameter tells the printing daemon to wait for 5 minutes
before designating a print job as frozen. The default is 2 minutes
(grrr!). The second line is the important one, as it tells the daemon
to not keep any finished jobs in the queue.
All Good
Now everything is happy. You can browse the Samba printer, and your
jobs actually go away when they're done printing! Of course, this
system will probably introduce other problems (re-queueing of jobs
comes to mind), but it works here. If you're having issues, email me.
If It Ain't Broke Then Fix It
To move to Cups printing, you first have to set the printing system to use cups. You then have to make a few more edits for samba. First set cups as the default printing system:
# /usr/sbin/alternatives --config print
reading /var/lib/alternatives/print
There are 2 programs which provide 'print'.
Selection Command
-----------------------------------------------
1 /usr/bin/lpr.cups
*+ 2 /usr/bin/lpr.LPRng
Enter to keep the default[*], or type selection number:
Type 1 and hit enter. Now would be a good time to stop the current LPRng pring server, and to start the new cups print server:
# service lpd stop
# service cups start
You have to now set up the printer. Point a web browser on the local machine to http://localhost:631. Log in as the root user.
Now to edit the samba config files to use cups printing. First, change line 38 in /etc/samba/smb.conf from:
printing = lprng
to
printing = cups
Then, uncomment line 83 in /etc/cups/mime.convs:
#application/octet-stream application/vnd.cups-raw 0 -
and also uncomment line 152 in /etc/cups/mime.types:
#application/octet-stream
Restart the samba services from the shell:
# service smb restart
Update for PLC Printers
Dave Cinege wrote to give a tip for anyone with a Lexmark Optra R+, or any other printer that supports both PLC and PS inputs. Even after following the above the printer still refused to work. As Dave remarked:
Here's why: I was using a the native Postscript driver under Windows, and
CUPS was filtering and (trying to) process this. Switch the w2k client
to use the PLC, fixed all. I've not taking the time to figure out how to fix
it right (IE PS from w2k doesn't make CUPS croak). I'll leaving that to
someone with more time.
If you've gotten any of those extremely annoying spams that
advertize free university diplomas and such, here's how to get rid of
them. Go into Administrative Tools->Services. Open up the Messenger
service. Change the startup type to manual, and be sure to stop the
service immediately.
So you know about "uptime" on Linux, to see how long the computer has been up. What's the equivalent on Windows, to see how long it's been since the last major security hole was patched? (5 days in my case) A simple way is to use the "net" command:
net statistics workstation
At the top of the output, which may scroll out of the immediate terminal view, you'll see the line:
Statistics since XX/XX/XXXX XX:XX XX
Now, this value is tied to networking, but who runs a machine without networking anymore?
Found this great site today that shows how to keep your console programs from automatically terminating, in both Unix and Win32. The relevant code is:
#include <windows.h>
#include <iostream.h>
int main(int argc, char* argv[])
{
HANDLE hStdIn;
DWORD numIn;
CHAR c;
cout << "Press any key to continue" << endl;
hStdIn = GetStdHandle(STD_INPUT_HANDLE);
SetConsoleMode( hStdIn, ENABLE_PROCESSED_INPUT );
FlushConsoleInputBuffer( hStdIn );
ReadConsole(hStdIn, &c, 1, &numIn, NULL );
return 0;
}
If you've ever gotten the error message:
mkfs.msdos: unable to allocate space for FAT image in memory
try first overwriting the disk with all zeros:
$ dd if=/dev/zero of=/dev/fd0
Replace /dev/fd0 with the appropriate device node that you are trying to format.
PDFLatex keeps giving you A4 sized documents? Running texconfig doing nothing to change that? Here's how to fix it. Open /usr/share/texmf/pdftex/config/pdftex.cfg in your text editor. Change the lines:
page_width 210truemm
page_height 297truemm
to
page_width 215.9truemm
page_height 279.4truemm
Viola! More information here.
If you're getting
Xman Error: No manual pages found.
Add the following lines to /etc/profile
MANPATH=/usr/share/man:/usr/man
export MANPATH
Log out and log back in.
Update! (26 October 2002) I'm happy to report that in my install of Red Hat 8.0, xman works just fine by default.
If you're seeing crazy characters in your Konsole when viewing man pages, yet plain old xterm works fine, here's what I found. The default language chosen by Red Hat in 8.0 is
en_US.UTF-8
not the usual
C
So, as root edit /etc/profile.d/lang.sh, and make the last two lines of the file:
LANG=C
export LANG
Log out, and log back in.
So you've noticed that your brand spanking new GeForce 4 card has 2 monitor outputs. You have that ancient 17" in the closet... maybe you could use it for keeping some of those xterms always in view. That was my plan anyway. I bought a Gainward Ultra/650 TV card, so YMMV with other versions.
First off, you must be running the official NVidia drivers. If you have an NVidia card and you're running the standard XFree86 drivers, upgrade immediately, even if you're not doing OpenGL or 3D gaming, because this dual monitor stuff requires features that only the official drivers support.
Once you're running the official drivers, read the NVidia README to determine how you want your monitors configured. Here's how I did it:
Section "Device"
Identifier "Videocard0"
Driver "nvidia"
VendorName "Videocard vendor"
BoardName "NVIDIA GeForce 4 (generic)"
BusID "PCI:1:0:0"
Screen 0
Option "NoLogo"
Option "CursorShadow" "on"
Option "CursorShadowXOffset" "2"
Option "CursorShadowYOffset" "2"
Option "TwinView"
Option "TwinViewOrientation" "RightOf"
Option "MetaModes" "1280x1024,1024x768; 1280x1024,NULL"
Option "ConnectedMonitor" "CRT, CRT"
Option "SecondMonitorHorizSync" "30.0 - 50.0"
Option "SecondMonitorVertRefresh" "60.0 - 70.0"
Option "IgnoreEDID" "true"
EndSection
My setup consists of a beautiful Samsung 19", and a rather old Sony 17". I wanted the Sony to be the right screen, as the left screen by default becomes the home screen, with your panel and such. So, the above options turn on TwinView (that's how NVidia does the dual monitor with XFree86), sets the resolutions for the monitors, tells the card that both outputs go to CRT screens, sets the refresh rates, and finally tell the card to ignore what it auto-detects.
This was necessary for me as my older monitor is not plug and play, and the card could not detect its settings. On Windows this made the monitor unusable, but on Linux you can override the driver defaults (more proof that Windows sucks). In the "MetaModes" line, you'll see two listings. The first is the default resolutions. The second is automagically activated when running one of the many great games for Linux. Without this, the game will default to the center of the X display area, which unfortunately is half on the left monitor and half on the right :-(
Some other options of note include turning off that stupid NVidia advertisement when starting X (NoLogo) and turning on the mouse cursor shadow, like Windows 2000/XP have. This is perhaps unnecessary, but I think it looks much better, and since it's probably done wholly in hardware, it won't affect your system performance much at all.
Here is my entire XF86Config file. Most is autogenerated, so don't expect drastic insight. I'm told that the next version of XFree86 will (finally!) allow for realtime GUI control of X resolutions, so editing this file by hand will hopefully become a thing of the past.
If you're trying out the newest Linux kernels (the 2.5 series) on Red Hat 8.0, here's a tip that nobody seems to make obvious. You need to upgrade your modutils package, otherwise you'll get this message whenever you try doing anything module-related:
QM_MODULES: Function not implemented
Install the appropriate modutils source code package:
rpm -Uvh http://www.kernel.org/pub/linux/kernel/people/rusty/modules/modutils-2.4.21-11.i386.rpm
Then, build the package:
rpmbuild -bb /usr/src/redhat/SPECS/modutils.spec
And finally, install the new package:
rpm -Uvh --force /usr/src/redhat/RPMS/i386/modutils-2.4.21-11.i386.rpm
To back up a directory from a remote machine to your local account, use the following command:
ssh otherhost.yourdomain.net "tar cvfz - /home/account" > backup.tar.gz
On slower machines, you may want to leave off the compression:
ssh otherhost.yourdomain.net "tar cvf - /home/account" > backup.tar
Note: I originally saw this somewhere else, but I found this great tip again here.
Having installed Fedora Core 1, my computer was having just the strangest issues with my standard 3Com ethernet card. I was getting bizarre messages like:
eth0: Transmit error, Tx status register d0.
Also, my event log was just filled with interesting 3c59x driver error messages.
I found the solution here. Add to your /etc/modules.conf file (as root):
alias eth1 3c59x debug=0 options=4 full_duplex=1
The Nvidia supplied Linux driver packages won't compile by default on Fedora Core 1. I found a solution here. First download the Nvidia Linux drivers (they were here the last I checked). Then, as root, run the following commands:
rpm -e --nodeps XFree86-Mesa-libGL
sh NVIDIA-Linux-x86-1.0-4496-pkg2.run --add-this-kernel
sh NVIDIA-Linux-x86-1.0-4496-pkg2-custom.run
The Nvidia installer program should be pretty self explanatory. Modify your /etc/X11/XF86Config file to look something like this:
Section "Module"
Load "dbe"
Load "extmod"
Load "fbdevhw"
Load "glx"
Load "record"
Load "freetype"
Load "type1"
Load "dri"
EndSection
The important modules are the glx and dri ones. I've had no problems so far by doing this.
Make a new text document. Set the margins and paper size. Save the
file as an OpenOffice Template, in ~/.openoffice/user/templates/default
. Open File->Templates->Organize. Double click on the default folder,
right click on the filename that appears, and then select "Set as
Default Template".
You may also want to set the default paper under Printer Administration, under the File menu.
If you are sharing a directory with Apache, yet don't want say the MPAA to be able to read it, you can limit access to that folder by domain name. Open httpd.conf and change the line:
AllowOverride None
To:
AllowOverride AuthConfig Limit
For me, with the standard Red Hat configurations, this is line 487 in Red Hat 7.3 and line 329 in Red Hat 8.0. Then, in your directory, create a text file named ".htaccess". Make the contents of that file like the following:
deny from all
allow from sis.pitt.edu
allow from cmu.edu
Change the domain names to what you want of course.
If you work frequently with angles and triangles like I do, you'll often come across the problem of computing the angle associated with two sides of a right triangle. Here's my code to get the angle:
// first get the angle from atan
rotation = atan(dy / dx) * 180.0 / 3.14159265;
// then convert into the conventional 0 - 360 degrees format
if(dy <= 0.0 && dx >= 0.0) {
rotation += 180.0;
} else if(dy <= 0.0 && dx < 0.0) {
// nothing to do here
} else if(dy > 0.0 && dx >= 0.0) {
rotation += 180.0;
} else if(dy > 0.0 && dx < 0.0) {
rotation += 360.0;
}
I spent hours and hours trying to understand how to convert the
Euler angles in DIS entity state PDUs into conventional pitch, roll,
and yaw. I eventually found the answer buried in OTBSAF source code,
which I've cleaned up and condensed. I've only tested heading, and
even then the arguments were reversed in the original source, so you
might have to experiment a bit to get it right. Please drop me a line if you try the
code.
/* psi, theta, and phi from entity state PDU */
double cos_psi = cos(psi);
double sin_psi = sin(psi);
double cos_theta = cos(theta);
double sin_theta = sin(theta);
double cos_phi = cos(phi);
double sin_phi = sin(phi);
double rot[3][3]; /* Rotation matrix */
#define X 0
#define Y 1
#define Z 2
rot[X][X] = sin_psi * cos_theta;
rot[X][Y] = cos_psi * cos_phi + sin_psi * sin_theta * sin_phi;
rot[X][Z] = - cos_psi * sin_phi + sin_psi * sin_theta * cos_phi;
rot[Y][X] = cos_psi * cos_theta;
rot[Y][Y] = - sin_psi * cos_phi + cos_psi * sin_theta * sin_phi;
rot[Y][Z] = sin_psi * sin_phi + cos_psi * sin_theta * cos_phi;
rot[Z][X] = sin_theta;
rot[Z][Y] = - cos_theta * sin_phi;
rot[Z][Z] = - cos_theta * cos_phi;
double pitch = asin(rot[Y][Z]);
pitch *= 57.29577951308232087679; /* Convert to degrees */
if(pitch < 0.0) pitch += 360.0;
if(pitch > 360.0) pitch -= 360.0;
double roll = atan2(rot[Z][Z], -rot[X][Z]);
roll *= 57.29577951308232087679; /* Convert to degrees */
if(roll < 0.0) roll += 360.0;
if(roll > 360.0) roll -= 360.0;
double yaw = atan2(rot[Y][X], rot[Y][Y]);
yaw *= 57.29577951308232087679; /* Convert to degrees */
if(yaw < 0.0) yaw += 360.0;
if(yaw > 360.0) yaw -= 360.0;
Ok, so this really isn't a computer tip, sue me. Wait, I'm not
serious! Anyway, this is one of my favorite recipes from home. It's
simple (always a plus) and quite tasty too. Enjoy. (Copyright whoever
owns this recipe)
A very fast and easy dish that will please the whole family.
1 pound boneless skinless chicken breasts -- cut into strips
2 tablespoons oil
1 can chicken broth
8 oz tomato sauce
1 package taco seasoning mix (make your own)
1 1/2 cups instant rice -- uncooked
1/2 cup shredded cheddar cheese
tortilla chips
In a skillet with a cover, saute the chicken in the oil until
opaque. Drain. Add chicken broth, tomato sauce, and taco seasoning
mix. Bring to a boil and simmer, covered for about 5 minutes, stirring
occasionally. Stir in the instant rice, cover, remove from heat and let
stand 5 minutes, until rice is tender.
Fluff with a fork, sprinkle with cheese and serve immediately, with
tortilla chips.
I've been searching for some time for a simple recipe like this, to make muffins out of normal cereal. I'm assuming that this works just as well with raisin bran, but I haven't tested it yet. I found this at http://www.mrbreakfast.com/superdisplay.asp?recipeid=1009.
Corn Flake Muffins
(12 servings)
1 and 1/4 cups all-purpose flour
1 Tablespoon baking powder
1/2 teaspoon salt
1/4 cup sugar
2 cups corn flakes
1 and 1/4 cup milk
1 egg
1/3 cup vegetable oil
Sift together flour, baking powder, salt and sugar. Set aside.
Stir corn flakes and milk together in a separate large mixing
bowl. Let stand about 2 minutes until cereal is softened. Add egg and
oil to this mixture. Beat well. Add flour mixture to wet mixture,
stirring only until combined. Portion butter evenly into 12 lightly
greased 2-1/2-inch muffin pan cups.
Bake at 400 degrees about 20 minutes or until lightly browned. Serve
warm.
Be aware of your oven. Mine runs hot and 30 minutes at 350 degrees
works better for me.
