gaim-latex plugin

There’s a very nice plugin for Gaim that allows one to send latex code via IM to other people who have the same plugin (if they don’t they just see the latex code).

I find it very usefull since I’m a student in a math department and I often exchange math fomulae with people even through IM.

I wonder how one would describe this latex code in “normal IM text”:

$$ f( x) =
\sum_{i=0}^{\infty}\frac{f^{( i )}(x )}{i!} $$

but…check this:
gaim-latex plugin for Gaim in action

If you exchange math formulae with colleagues via IM … you’ll want this one 🙂

scroll more lines with mouse wheel on acroread

edit your .Xdefaults and add this at the bottom:

*XmScrollBar.baseTranslations:#augment\n Shift:IncrementUpOrLeft(0)\n Shift:IncrementDownOrRight(0)\n :IncrementUpOrLeft(0)IncrementUpOrLeft(0)IncrementUpOrLeft(0) IncrementUpOrLeft(0)IncrementUpOrLeft(0)IncrementUpOrLeft(0)\n :IncrementDownOrRight(0)IncrementDownOrRight(0)IncrementDownOrRight(0) IncrementDownOrRight(0)IncrementDownOrRight(0)IncrementDownOrRight(0)\n

That’s ONE line! Then to test it open a pdf with acrobat reader on linux and press shift while scrolling the mouse wheel…you’ll notice the difference 🙂 (it now scrolls one page per scroll “click”)

enjoy 🙂

the right way to enable udev in gentoo

I know there are numerous postings and wiki articles on the net on how to enable udev on a linux distribution and specifically for Gentoo. Because I did not find anything complete here’s my version on doing all that. The were 2 reasons I started looking around for udev support, first reason was to have a special device for my olympus c70z so I did not have to “fdisk -l” every time I wanted to check on what device it was, and secondly to improve the usb_key+hotplug+xlockmore stuff I had done earlier.

I am not writing this guide for complete newbies to linux and kernel stuff…I am not going to explain how to compile a kernel and where to put it and and and and…cause it would never end.

First thing to do check your kernel settings!!

Device Drivers -> USB Support
< *> Support for Host-side USB
[*] USB device filesystem
< *> EHCI HCD (USB 2.0) support
< *> OHCI HCD support

For SCSI support
Device Drivers -> SCSI device support
[*] legacy /proc/scsi/ support
< *> SCSI disk support
< *> SCSI generic support

For vfat file system support
File systems -> DOS/FAT/NT Filesystems
< *> MSDOS fs support
< *> VFAT (Windows-95) fs support

Remove devfs support (If you want...)
File systems -> Pseudo filesystems
[ ] /dev file system support (OBSOLETE)
BUT YOU MUST REMOVE !!!! below devfs support.
[ ] Automatically mount at boot (SAY NO TO THIS!!!!)

Then emerge the proper packages:
emerge -uDv udev hotplug baselayout

Edit your /etc/conf.d/rc:
You must have settings like that:

sysctl -w kernel.hotplug="/sbin/udev"
rc-update add hotplug boot

In lilo.conf change the append line of your kernel adding this:
and then type lilo to make the proper changes.

If you rebooted now your system with the new kernel it should have been udev enabled.

You might encounter mouse problems, because the old /dev/mouse symlink is lost with udev. Edit /etc/conf.d/gpm and /etc/X11/xorg.conf to replace /dev/mouse with /dev/input/mouse0

What’s next ? udev rules. You must make some rules for udev to properly find your devices.
I am going to explain how I wrote 3 simple rules for my digital camera, my usb stick and my usb-hdd.
When plugged in the usb port go check your dmesg. You should see something like:
Attached scsi removable disk sdb at scsi7, channel 0, id 0, lun 0
Attached scsi generic sg1 at scsi7, channel 0, id 0, lun 0, type 0

now do this: udevinfo -a -p /sys/class/scsi_generic/sg1
and a bunch of info like that will appear in front of you:
looking at the device chain at '/sys/devices/pci0000:00/0000:00:10.0/usb2/2-2':
SYSFS{bMaxPower}=" 0mA"
SYSFS{bNumInterfaces}=" 1"

SYSFS{version}=" 2.00"

We just need the italic ones.
edit /etc/udev/rules.d/10-local.rules
and add something like this:
BUS="usb", KERNEL="sd?1", SYSFS{manufacturer}="OLYMPUS", SYSFS{serial}="1234567890", SYSFS{product}="C70Z,C7000Z", NAME="%k", SYMLINK="c70z"


now “mkdir -p /mnt/digicam” and add something like this in your /etc/fstab:
/dev/c70z /mnt/digicam vfat noatime,user,rw,sync,uid=1000 0 0

mount /mnt/digicam and your camera is ready to extract the pictures from it!

same as above…but the rule and fstab entry will defer slightly:
udev rule:
BUS="usb", SYSFS{serial}="23DE746790310A9B", NAME="%k", SYMLINK="mykey"
fstab entry:
/dev/mykey /mnt/usbkey vfat noatime,user,rw,sync,uid=1000 0 0

udev rule:
BUS="scsi", SYSFS{model}="00JB-32EVA0", NAME{all_partitions}="wd-usb"
fstab entry:
/dev/wd-usb1 /mnt/usbdisk ext3 noatime,users 0 0

Remember my old post on pam_usb ? It gets a lot better with udev!
edit /etc/pam.d/login
and change the rule into something like this now:
auth sufficient /lib/security/ proc_basename=/proc/scsi/usb-storage/1 !check_device force_device=/dev/mykey allow_remote=1 fs=vfat debug=1 log_file=/var/log/pam_usb.log

where /dev/mykey is created by udev so it does not matter where the real device is…it will always symlink to mykey!

You can’t make it work ? Read these links…they might help you:
Gentoo udev Guide
Gentoo Wiki – HOWTO_Install_a_digital_camera
UDEV Primer
Using udev for Static Device Naming
Writing UDEV rules

usbutils problems and solution

I just wanted a tool to easily monitor my usb devices, and that should be lsusb . In Gentoo it’s inside usbutils package, but when I tried to emerge it I got a ton of errors like that:

In file included from /usr/include/linux/usb.h:4,
from access.c:34:
/usr/include/linux/mod_devicetable.h:18: error: syntax error before "__u32"
/usr/include/linux/mod_devicetable.h:20: error: syntax error before "class"
/usr/include/linux/mod_devicetable.h:21: error: syntax error before "driver_data"
/usr/include/linux/mod_devicetable.h:31: error: syntax error before "__u32"
/usr/include/linux/mod_devicetable.h:33: error: syntax error before "model_id"
/usr/include/linux/mod_devicetable.h:34: error: syntax error before "specifier_id"
/usr/include/linux/mod_devicetable.h:35: error: syntax error before "version"
/usr/include/linux/mod_devicetable.h:36: error: syntax error before "driver_data"
/usr/include/linux/mod_devicetable.h:99: error: syntax error before "__u16"
/usr/include/linux/mod_devicetable.h:103: error: syntax error before "idProduct"
/usr/include/linux/mod_devicetable.h:104: error: syntax error before "bcdDevice_lo"
/usr/include/linux/mod_devicetable.h:105: error: syntax error before "bcdDevice_hi"
/usr/include/linux/mod_devicetable.h:108: error: syntax error before "bDeviceClass"
/usr/include/linux/mod_devicetable.h:109: error: syntax error before "bDeviceSubClass"
/usr/include/linux/mod_devicetable.h:110: error: syntax error before "bDeviceProtocol"
/usr/include/linux/mod_devicetable.h:113: error: syntax error before "bInterfaceClass"
/usr/include/linux/mod_devicetable.h:114: error: syntax error before "bInterfaceSubClass"
/usr/include/linux/mod_devicetable.h:115: error: syntax error before "bInterfaceProtocol"
/usr/include/linux/mod_devicetable.h:118: error: syntax error before "driver_info"
/usr/include/linux/mod_devicetable.h:135: error: syntax error before "__u16"
/usr/include/linux/mod_devicetable.h:138: error: syntax error before "dev_type"
/usr/include/linux/mod_devicetable.h:139: error: syntax error before "cu_model"
/usr/include/linux/mod_devicetable.h:140: error: syntax error before "dev_model"
/usr/include/linux/mod_devicetable.h:142: error: syntax error before "driver_info"
/usr/include/linux/mod_devicetable.h:155: error: syntax error before "__u8"
/usr/include/linux/mod_devicetable.h:160: error: syntax error before "__u8"
/usr/include/linux/mod_devicetable.h:163: error: syntax error before "__u8"
/usr/include/linux/mod_devicetable.h:165: error: syntax error before '}' token

The solution was to edit /usr/src/linux/include/linux/usb.h and comment out lines 4 and 5:

4 /*#include 5 #include */

Then I emerged usbutils just fine…uncommented the previous lines…and everything is working properly:

# lsusb
Unknown line at line 1809
Duplicate HUT Usage Spec at line 2650
Bus 004 Device 004: ID 058f:9254 Alcor Micro, Inc. Hub
Bus 004 Device 001: ID 0000:0000 Virtual Hub
Bus 003 Device 001: ID 0000:0000 Virtual Hub
Bus 002 Device 001: ID 0000:0000 Virtual Hub
Bus 001 Device 002: ID 05e3:0702 Genesys Logic, Inc.
Bus 001 Device 001: ID 0000:0000 Virtual Hub

distcc with gentoo

I wanted to install gentoo on an old pII at 400MHz I own. The compilation time would take really really long if it was done on that machine only…that’s where I thought about installing distcc to my other gentoo machines. I followed Gentoo Distcc Documentation and in a few minutes I was able to compile stuff concurrently between 3 different machines, an athlonxp 2800+, an athlonxp 2500+ and and that pII 400MHz. I edited /etc/make.conf and replaced

The machines were all i686 and the whole process was a lot faster than it would if I compiled only at that old pII. I am now running an emerge –emptytree just to check if all will be compiled cleanly with distcc without problems.

cancelling echo in audigy2 for voip applications in linux

big title huh?

I had tried various applications for VoIP in Linux, Gnomemeeting, kphone, skype, etc etc and I was always told that the remote party heard an echo of his/her voice. My side was perfect…but the opposite side was unacceptable.
The solution to the echo problem was to tweak audigy2 capture values in alsamixer or alsamixergui.

Fire up alsamixer…you should probably see that the “View: ” title on top says “Playback”. Go to microphone and set it down to 0..that’s Then press tab once and the “View: ” title will switch to “Capture”. Set PCM capture to 0 (zero) and mic value around 80-90.
The mic boost (+20db) is usefull to me too…use it if you want.
In alsamixergui: set the first PCM slider as high as you want and the second one to zero. Then go to mic and set the first to zero and the second one to 80-90.

After that the remote parties I talked to stopped bugging me about echo problems. So I think that’s the solution.