Linux Tips

POstfix

2005-10-12T14:09:00.000-07:00

Did a quick postfix setup...could send mails but could not receive...the culprit was teh router which was blocking port 25.

DRUPAL /usr/share/doc/drupal/README.Debian.gz

2005-08-05T20:04:00.000-07:00

/usr/share/doc/drupal/README.Debian.gz

Saaala

2005-08-05T00:10:00.000-07:00

All perl modules in Hoary Hedgehog are managed by the apt-get/synaptic system?
Damn...and i was MCPANing them all the while...

SCP Funda

2005-07-25T16:56:00.000-07:00

The syntax for SCP is almost identical to the regular cp command for copying files, but with an added syntax for specifying the server the filesystem resides on:

scp [user@host:] [user@host:]

For example, to copy xyz.cpp from the current directory to my home directory on bakwaas.homelinux.net, I would type this:

scp xyz.cpp mylogin@bakwaas.homelinux.net:/home/mylogin

Usage in Perl

2005-07-25T12:04:00.000-07:00

unless ( @ARGV == 1){
die "usage:\.\\script_name ";

Important it is @ARGV and not $ARGV.

Movable Type

2005-07-15T21:46:00.000-07:00

So the jokers at Movable Type didnot update their manual for apache2. Had trouble to get the cgi scripts to run...

Did the following for it to work...
Added the following file to apache2.conf...

"< Directory /var/www/apache2-default >"
Options +ExecCGI
"< /Directory> "

the other instruction was correct that is...

Outside of the Directory or Location block, add the line
AddHandler cgi-script .cgi
Restart the webserver.

An the woes continued ...on running mt-load.cgi, the damn thing showed access denied...so figured from google that the user lacked create permissions...did a grant ALL on database.* to databaseuser@localhost...and things worked!

Ubuntu:How to mount network folders on boot-up, and allow all users to read/write?

2005-06-22T20:24:00.000-07:00

http://www.ubuntuguide.org/#mountunmountnetworkfolders

Rsync Vs Unison

2005-06-15T23:49:00.000-07:00

http://www.cis.upenn.edu/~bcpierce/unison/

Deleting Linux Partitions and Windows doesn't boot!!

2005-06-13T00:52:00.000-07:00

Okai, here is the situation..roomie's machine had a dual boot congiguration ( Windoze XP and Ubuntu)...the partition which had the linux installation was deleted ( from Administrator Tools in XP)...when rebooted, it would fail at grub! Couldn't boot into windows.
FIX:-
a) insert the original windows XP installation CD.
b) Press R to enter Recovery mode.
c) run chkdsk
d) run fixmbr
e) fixboot

reboot by typing exit on the command line.

How to remount /etc/fstab without rebooting?

2005-05-23T10:03:00.000-07:00

How to remount /etc/fstab without rebooting?

sudo mount -a

Perl Tip

2005-05-10T19:26:00.000-07:00

If you see an error which is similar to this...

Undefined subroutine &main::convert_date called at ./script4.pl line 54, line 4.

Then most likely there is a 'locha' in the subroutine ( this is perl's way of givingya a compilation error!)

Microshaft Eqn Editor

2005-05-04T20:38:00.000-07:00

Okai, not technically a *nix post..but here it goes...
occasionally I find that I don't get the toolbar to edit a MS eqn, what needs to be done is View-> Toolbar and bingo the toolbar is there for ya.

Mounting UNIX and Windoze Shares on Mac OS X

2005-05-02T16:55:00.000-07:00

Easy...

UNIX
Finder->Go->Connect to Server-> ftp://unixbox; say yes to mount dialog box that pops up.
Windoze
Same as above except
->smb://Windoze Box IP; say yes again.

Done

FSCKING DATABASES

2005-04-03T14:30:00.000-07:00

FSKING code for creating a fscking database with fscking tables in 'em.

god@ubuntu:~ $ sudo mysql -p -u root
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 947 to server version: 4.0.20-log

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> create database webdb;
Query OK, 1 row affected (0.04 sec)

mysql> GRANT SELECT, INSERT, UPDATE, DELETE ON webdv.* TO webdev@localhost;
Query OK, 0 rows affected (0.12 sec)

Better still..since the prev command does not grant create privileges..we can have...
mysql> GRANT ALL ON webdv.* TO webdev@localhost;
Query OK, 0 rows affected (0.12 sec)

Okai, these fscking databases never fail to amaze me...so today i discovered that there were duplicate rows in the table!! Yikes....read up a lil bit here..
But thazz okay, if that link is not there..apparently this is the right way to create tables...

create table ADDED(Developer CHAR(20) NOT NULL,FILE_OR_DIR CHAR(150) NOT NULL,PRIMARY KEY(Developer,FILE_OR_DIR));

create table MODIFIED(Developer CHAR(20) NOT NULL,FILE_OR_DIR CHAR(150) NOT NULL,Count INT,PRIMARY KEY(Developer,FILE_OR_DIR));

Installing Perl Modules

2005-03-26T19:04:00.000-08:00

Two steps...

perl -MCPAN -e shell

cpan> install

Importing mbox files into Thunderbird

2005-02-21T10:16:00.000-08:00

This is the easiest way (I think...correct me)
1) Download the mbox archive say allmails.mbox to your homedir ~/
2) from the thunderbird interface create a folder in your Local Folders, say call it Newmails
2) navigate to your local folders
a) cd ~/.mozilla-thunderbird/5zcblahblah.default/Mail/Local Folders
b) confirm that Newmails and Newmails.msf exist.
c) cp ~/allmails.mbox .
d) rm Newmails # remove the Newmails file only not the .msf file
e) mv allmails.mbox Newmails
3) restart Thunderbird
4) Click on Newmails, depending upon the size, the messages may take a while to load.

sed tip

2005-02-21T09:41:00.000-08:00

To delete the first 1000 lines from a file

$ sed '1,100d' filename.txt > outputfile.txt

the sed -e option is reqd only if you are using multiple editing commands on the same instance of sed.

Drupal

2005-02-10T21:44:00.000-08:00

Drupal Installation was staright forward except for..when I did everything right and then type http://localhost, I would get...
Fatal error: Call to undefined function: mysql_connect() in /var/www/apache2-default/includes/database.mysql.inc on line 31

Went bonkers for quite sometime figuring out what the hell is going on?

Checked the php.ini file in /etc/php4 and uncommented the relevant part, i.e
### Copied and pasted from php.ini

;;;;;;;;;;;;;;;;;;;;;
; Dynamic Extensions ;
;;;;;;;;;;;;;;;;;;;;;;
;
; If you wish to have an extension loaded automatically, use the following
; syntax:
;
; extension=modulename.extension
;
; For example, on Windows:
;
; extension=msql.dll
;
; ... or under UNIX:
;
; extension=msql.so
;
; Note that it should be the name of the module only; no directory information
; needs to go here. Specify the location of the extension with the
; extension_dir directive above.

; Example lines:

extension=mysql.so
;extension=gd.so

##End of copy and paste

Even then the thing would not work....the same error messages...
After a lot of head banging, figured that I did't have the module ...duh!!!
Went over to synaptic and marked for installation...the package is called php4-mysql

and lo ...things worked!

Perl's CPAN Preferences

2005-02-05T11:01:00.000-08:00

To alter the CPAN preferences, either edit the Config.pm configuration file manually, or use the following command in the CPAN shell.

cpan> o conf init

The init configuration option runs through all the configuration questions, which may be time consuming. For example, other o conf commands can be used to list, remove, and add mirror sites, and then to save the changes to disk.

cpan> o conf urllist
urllist
ftp://ftp.kernel.org/pub/CPAN/
Type 'o conf' to view configuration edit options

cpan> o conf urllist shift

cpan> o conf urllist push ftp://ftp-mirror.internap.com/pub/CPAN/

cpan> o conf urllist
urllist
ftp://ftp-mirror.internap.com/pub/CPAN/
Type 'o conf' to view configuration edit options

cpan> o conf commit
commit: wrote /usr/local/lib/perl5/5.6.1/CPAN/Config.pm

To manually edit the existing configuration file, either open the user-specific ~/.cpan/CPAN/MyConfig.pm directly, or locate the system-wide configuration file (stored somewhere under the perl @INC path list) to edit with the following command.

$ perl -le 'for (@INC) { $_ .= $ARGV[0]; print if -f }' /CPAN/Config.pm
/System/Library/Perl/CPAN/Config.pm

Mathematica Woes

2005-01-05T22:37:00.000-08:00

Had a huge issue trying to get mathematica 4.1 installed on apache to correctly talk to my X-server on Ubuntu. Every time i launched Mathematica I would run into problems, here is what i posted on the mathematica usenet

Dear friends,
I am running ubuntu Linux 2.6.8.1-3-386 on a pentium 4 machine. I am trying to get Mathematica run from remote server running SunOS apache 5.9 Generic_112233-12 sun4u sparc SUNW,Sun-Fire-880.
So , I read all the instructions and download the Type1,BDF and PCG tar.gz files ,then I unpack them into a neat MathFonts directory I created for myself. I then add the following lines to my .bashrc file
##added for mathematica
xset fp+ /home/nick/MathFonts/Type1
xset fp+ /home/nick/MathFonts/BDF
xset fp+ /home/nick/MathFonts/PCF
xset fp rehash

I then open a different xterm and do a ssh -X -C hostname_where_mathematica_runs, I login and punch mathematica enthusiastically...
I see the Mathematica splash-screen coming on my local machine..coool...
and then Mathematica complains that it can't find the needed fonts...too bad :( , i say continue..Mathematica says it can't find Math1 fonts and then defaults to courier.

So friends , where am i going wrong?? I have tried to read all the related posts and stuff on the internet , but everything seems to be in accordance.

Any tips would be heartly appreciated!

-Nick

Well this is what I got from a website , I did thefollowing and it worked!!

First ftped to apache.
Then downloaded the entire apache:/usr/local/mathematica/SystemFiles/Fonts/X directory to my homedir.
then on ubuntu did the following...
cd /usr/X11R6/lib/X11/fonts
cp -r 75dpi 75dpi.orig
cd 75dpi
cp /home/nick/X/*.bdf .
mkfontdir

Voila!

zope and plone

2004-12-27T15:02:00.000-08:00

zope and plone, originally uploaded by Nick00.

Had a tough time trying to figure out why I can access my Plone site and Zope Management Interfaces on the machine where it is hosted but not on others? Turns out that the Windows SP2 firewall had blocked all acess to ports 80 and 8080; I freed these and every thing seems fine.

Sudo

2004-12-16T13:56:00.000-08:00

Had some trouble with sudo of late..basically added jpeg to the sudo file...
and then found that sudo never prompted him for a password..did everything including using the PASSWD and NOPASSWD options, all the usual stuff that you find on the net...
figured out that jpeg was a member of sudo and staff groups..removed him from these groups and everythings fine as usual...

Herez my current sudoers file.

# sudoers file.
#
# This file MUST be edited with the 'visudo' command as root.
#
# See the man page for details on how to write a sudoers file.
#

# Host alias specification

# User alias specification

# Cmnd alias specification

# Defaults
Defaults:jaideep timestamp_timeout =0,lecture,insults,tty_tickets,mailto = "me@yahoo.com",mail_always

# User privilege specification
root ALL=(ALL) ALL

# Added by Ubuntu installer
me ALL=(ALL) ALL
jpgeg ALL=(ALL) ALL

DSC00014

2004-12-14T22:25:00.000-08:00

DSC00014, originally uploaded by Nick00.

The CPU

Added FTP service at Boot time

2004-10-03T11:22:00.000-07:00

by adding the following line in /etc/rc.d/boot.local

pure-ftpd &

Making the Mouse Scroll Wheel Work

2004-09-24T10:55:00.000-07:00

My comments
This tip worked like a charm.Also remember that in Suse9.1; the Xserver is restarted every time you log out.

by Michael

A common problem I've had after installing Linux or upgrading XWindow is that my mouse's scroll wheel doesn't work. Fixing this in XFree86 is easy. On my system, which is RedHat, I edit /etc/X11/XF86Config-4 to change my X config. It may be in a different location on your system. Be sure to make a backup before editing this important configuration file.

At the top of this file should be a 'ServerLayout' section. In this section look to see what your InputDevice CorePointer is. Usually it will be identified as 'mouse0'. When you find out what your pointing device is look through the config file until you find an 'InputDevice' section with the identifier you are using. It should be using a 'mouse' driver.

In this section you'll need to change or add several options. Change the protocol to 'imps/2'. Add a 'buttons' option set to '5'. Add a 'ZAxisMapping' option set to '4 5'. Make sure that the 'Emulate3Buttons' option is set to 'no'. The finished section should look something like this:

Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "imps/2"
Option "Device" "/dev/psaux"
Option "Buttons" "5"
Option "ZAxisMapping" "4 5"
Option "Emulate3Buttons" "no"
EndSection

Restart your X server and you should find your scroll wheel working. Some applications don't support the scroll wheel so if you are still having trouble try using a different application. If the scroll wheel still doesn't work for you then most likely you have a non-standard mouse and will need to try something else to activate the wheel.

Copyright ©2004 Michael Ogmios. Content may be copied and distributed in full or part as long as this copyright notice is attached.

Yoper Linux

2004-09-21T18:56:00.000-07:00

http://www.yoper.com/

Yoper seems like a promise!

An introduction to Linux sound systems and APIs

2004-08-10T01:36:00.000-07:00

An introduction to Linux sound systems and APIs

Monday August 09, 2004 (04:00 PM GMT)

By: Christian Vincenot

When coding a program, one of the best ways to show users that an event has happened is to produce sounds. That's why sound is now present in almost every program. Every operating system has different sound systems and APIs to access the sound card, so that no low-level coding is required to use the sound device. Programmers have many different choices concerning which system to use, especially under Linux -- and maybe that's the problem. This article will illustrate free sound architectures under Linux, as well as the different interfaces a programmer can use.

Kernel sound drivers: OSS and ALSA

The most direct way is to talk to the kernel sound drivers . Linux has two

Open Sound System

Open Sound System (OSS) comes in two versions: OSS/Free, which is a free software maintained by the well-known kernel hacker Alan Cox, and 4Front Technologies' OSS (OSS/Linux, formerly known as VoxWare, USS, and TASD), which is a proprietary implementation based on OSS/Free. OSS is available not only for Linux but also for BSD OSes and other Unixes. That may be its only advantage, because this system is not very powerful and was officially replaced by ALSA in 2.5 kernels.

I'm not going to talk about programming for OSS, considering that it is deprecated, but it is not very difficult (to sum up, open /dev/dsp, /dev/dspW, or /dev/audio depending on the format you want, manipulate the file descriptor to read and write to the sound card, and use some ioctl to set parameters like volume). You can learn about advanced OSS programming in 4Front's API specs.

ALSA

Advanced Linux Sound Architecture (ALSA) is the new Linux sound hardware abstraction layer that replaces OSS. In fact, it's more than a simple HAL because it provides a user-space library named libasound. What's more, it's thread-safe, works well with SMP machines, and is backward-compatible with OSS/Free (using OSS emulation module). Of course, it's also free and open source. A full description of its features and API can be found on ALSA's Web site, and I would also suggest reading Paul Davis' Tutorial.

Let's take a look at ALSA's API with a little example that will show the good and bad points of ALSA:

/* Example stolen from Paul Davis' tutorial (don't worry, he won't sue me -- GPL privilege)
* Have just omitted the error handling for concision and added comments */

#include
#include
#include

main (int argc, char *argv[])
{
int i;
int err;
short buf[128];
snd_pcm_t *playback_handle;
snd_pcm_hw_params_t *hw_params;

/* Open the device */
snd_pcm_open (&playback_handle, argv[1], SND_PCM_STREAM_PLAYBACK, 0);

/* Allocate Hardware Parameters structures and fills it with config space for PCM */
snd_pcm_hw_params_malloc (&hw_params);
snd_pcm_hw_params_any (playback_handle, hw_params);

/* Set parameters : interleaved channels, 16 bits little endian, 44100Hz, 2 channels */
snd_pcm_hw_params_set_access (playback_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
snd_pcm_hw_params_set_format (playback_handle, hw_params, SND_PCM_FORMAT_S16_LE);
snd_pcm_hw_params_set_rate_near (playback_handle, hw_params, 44100, 0);
snd_pcm_hw_params_set_channels (playback_handle, hw_params, 2);

/* Assign them to the playback handle and free the parameters structure */
snd_pcm_hw_params (playback_handle, hw_params);
snd_pcm_hw_params_free (hw_params);

/* Prepare & Play */
snd_pcm_prepare (playback_handle);
for (i = 0; i < 10; i++) {
if ((err = snd_pcm_writei (playback_handle, buf, 128)) != 128) {
(...)
}
}

/* Close the handle and exit */
snd_pcm_close (playback_handle);
exit (0);
}

As you can see, the API is quite clear and not very hard to understand, even if it's a bit long. ALSA acts at a level low enough for the programmer to be able to chose another design called interrupt-driven or callback-driven, which is fundamentally better because:
There is no blocking on reads/writes.

The application is "driven" by the callbacks and can continue to run.

The code is easily portable to other sound systems.
The low-level capabilities of ALSA make it a powerful system, but code becomes very tricky when it comes to the full duplex with callbacks method, for which other sound systems may be preferrable. (Even the ALSA Audio API Tutorial advises using JACK for full duplex.)

About the practical use of Kernel Drivers...

Besides the full duplex difficulty, another problem for ALSA multimedia applications is what motivated the creation of sound servers: such programs need concurrent access to the sound card, and it's not possible to have only one application be able to produce and capture sound at a time. Practically, designers must determine at which level a program should act: If it needs low-level access, ALSA can be a good solution, but if sound is not the main part of the project or if high-level operations are needed, consider instead the sound systems we'll talk about next.

Sound servers

Sound servers are software that sit atop the audio core and put one more layer between the user and the hardware. The act of talking to the kernel's audio API comes with a little performance hit but results in a simpler API which enables applications to do software-based sample mixing. Software-based sample mixing enables applications to play multiple sounds at the same time on a single sound card without needing one a sound card that natively supports that. With it, applications can share the sound hardware, because sound servers support multiple channels (kernel sound servers support only one) by multiplexing and streaming the result to /dev/dsp. Some sound servers (esd, aRTs, NAS) are also built on a client/server model that enable sound to be played remotely and transparently on a network: this is called network transparency. If you want sound servers with such features, take a look at the Squeak homepage.

ESD

ESD, short for Enlightenment Sound Daemon, was originally developed for Enlightenment and is now part of the GNOME Project. ESoundD supports full duplex and network transparency, and is especially suited for sound effects and long unsynchronized music. You can extract the API from source: esd.h and esdlib.c. Compile with gcc -o esdtest esdtest.c `esd-config --cflags --libs`.

/* Let's see a skeleton that a recording program can change */
#include /* for NULL */
#include "esd.h"

int main()
{
char buf[ESD_BUF_SIZE];
int sock = -1;

/* Set format : 16bits stereo stream for recording */
esd_format_t format = ESD_BITS16 | ESD_STEREO | ESD_STREAM | ESD_RECORD;

/* And only 1 command to open the recording :) with the format defined earlier,
* ESD's default rate (ESD_DEFAULT_RATE -> 44100Hz),
* on localhost:16001 (default -> NULL), and with "testprog" as internal name */
sock = esd_record_stream_fallback(format, ESD_DEFAULT_RATE, NULL, "testprog");
if (sock <= 0) return 1;

/* And now treat that */
while (read(sock, buf, ESD_BUF_SIZE) > 0)
{
(...)
}
close(sock);
return 0;
}

Piece of cake, isn't it? The esd_record_stream function is in fact a wrapper that calls esd_open_sound(hostname) to connect to the server, negotiate with it, then sets the socket buffers size with esd_set_socket_buffers(sock, format, rate, 44100). The _fallback functions fall back to ALSA and OSS to try to play the sound if ESD fails, which is quite useful.

aRTs

The Analog RealTime Synthesizer is KDE's sound server. Support is progressively fading for it and it's probable that it will be abandoned in the future in favor of JACK. Nevertheless, various commentaries suggest that aRTs has better sound quality than ESD due to better sound processing routines (but higher latency too due to their complexity). aRTs also supports full duplex (but has been reported to be a bit buggy in this area) and network transparency and works on BSD operating systems. Documentation about the aRTs C API is quite rare (see the aRTs project Web site for a little page about it) so the best thing to do is to take a look at the source (artsc.h).

Here's a little example to compile with gcc -o artstest artstest.c `artsc-config --cflags` `artsc-config --libs`.

#include
#include

int main()
{
arts_stream_t stream;
char buffer[8192];
int bytes;
int errorcode;

/* Initialise aRTs with arts_init() */
if ((errorcode = arts_init()) < 0)
{
fprintf(stderr, "arts_init error: %s\n", arts_error_text(errorcode));
return 1;
}

/* Open a stream for playback at 44100Hz, 16 bits, 2 channels as "aRTstest" */
stream = arts_play_stream(44100, 16, 2, "aRTstest");

/* example of treatment : read music from stdin and play it with arts_write */
while((bytes = fread(buffer, 1, 8192, stdin)) > 0)
{
if ((errorcode = arts_write(stream, buffer, bytes)) < 0)
{
fprintf(stderr, "arts_write error: %s\n", arts_error_text(errorcode));
return 1;
}
}

/* Does what it says */
arts_close_stream(stream);
arts_free();

return 0;
}

The API is also very simple, as you can see. Some other useful commands include arts_suspend, to free the DSP device for aRTs-incapable programs to access it, and arts_stream_set, to configure some stream parameters.

JACK

JACK (also called JACKit) follows the long tradition of recursive acronyms -- in this case, Jack Audio Connection Kit. This project was created as an implementation of the Linux Audio Applications Glue API project, which aimed at creating a high-bandwidth, low-latency inter-application communication API. It is a real-time sound server written for POSIX systems (and actually available for Linux and OS X) that enables different applications to have synchronous connections to the audio hardware and to share audio among themselves via a ports system. Programs can run as normal independent applications or as plugins within the JACK server. It uses the callback method shown earlier, implements ringbuffers, and is, in my humble opinion, the most excellent and promising sound server. The only bad point is that it is not widely available at the moment, but that should be fixed soon. (Gentoo already includes it and there are some third party RPMs for Fedora Core.) The API is well-documented and available on SourceForge. A fully documented example for a capture client is available on Berman Home Page.

Here we'll start with something softer and smaller. Compilation is done using gcc -o jacktest `pkg-config --cflags --libs jack` jacktest.c.

/* Lighter version of simple_client.c */

#include
#include
#include
#include

jack_port_t *input_port;
jack_port_t *output_port;

/* Processing thread: only transmit the data from input to output */
int process (jack_nframes_t nframes, void *arg)
{
jack_default_audio_sample_t *out = (jack_default_audio_sample_t *) jack_port_get_buffer (output_port, nframes);
jack_default_audio_sample_t *in = (jack_default_audio_sample_t *) jack_port_get_buffer (input_port, nframes);

memcpy (out, in, sizeof (jack_default_audio_sample_t) * nframes);

return 0;
}

void jack_shutdown (void *arg)
{
exit (1);
}

int main ()
{
jack_client_t *client;

/* try to become a client of the JACK server */

if ((client = jack_client_new ("test_client") == 0) {
fprintf (stderr, "jack server not running?\n");
return 1;
}

/* tell the JACK server to call `process()' whenever there is work to be done. */
jack_set_process_callback (client, process, 0);

/* tell the JACK server to call `jack_shutdown()' if it ever shuts down, either entirely, or if it
just decides to stop calling us. */
jack_on_shutdown (client, jack_shutdown, 0);

/* display the current sample rate. once the client is activated */
printf ("engine sample rate: %lu\n", jack_get_sample_rate (client));

/* create two ports: 1 input & 1 output*/
input_port = jack_port_register (client, "input", JACK_DEFAULT_AUDIO_TYPE, JackPortIsInput, 0);
output_port = jack_port_register (client, "output", JACK_DEFAULT_AUDIO_TYPE, JackPortIsOutput, 0);

/* tell the JACK server that we are ready to roll */
if (jack_activate (client)) {
fprintf (stderr, "cannot activate client");
return 1;
}

/* connect the ports: input one to the first ALSA PCM input and output to the first ALSA PCM output */
if (jack_connect (client, "alsa_pcm:in_1", jack_port_name (input_port))) {
fprintf (stderr, "cannot connect input ports\n");
}

if (jack_connect (client, jack_port_name (output_port), "alsa_pcm:out_1")) {
fprintf (stderr, "cannot connect output ports\n");
}

/* Since this is just a toy, run for a few seconds, then finish */
sleep (10);
jack_client_close (client);
exit (0);
}

This code looks a bit more complex. To understand it, you must think of JACK as a big and complex switchboard with inputs and outputs and on which you can interconnect devices (microphone, sound card, programs, etc.) by plugging them into it. The program copies what's connected as input to what's connected as output (meaning, generally speaking, a wire or cable). This explanation is meant to be a simple example. If you want a complete analysis, go to dis-dot-dat.net.

All the handling is done in the callback and the main program flow is still running (that's why we've used sleep(10)). By the way, there are some real-time considerations when implementing the callback, like using non-blocking and deterministic calls only (malloc, printf, mutex_*, etc., must be banned). Here we're hard-coding a connection between our created output_port and alsa_pcm:out_1, but if you need something more flexible, an interesting function is jack_get_ports (client, NULL, NULL, JackPortIsPhysical|JackPortIsOutput), which for example gets a list of physical output ports available.

Practical implementation

So many APIs -- what now? What should a programmer wanting to use sound choose?
For somebody who wants to code a sound server or have a direct access to sound, ALSA is the obvious choice.

If you're sure that your program will run on only one destkop environment and will be closely linked to it, then choose ESD (for Enlightenment or GNOME) or aRTs (for KDE).

If your system doesn't need to be portable for the moment, Jack is full of promise.

For multi-systems/OS portability, join us tomorrow for part two of this discussion.

To be continued....

Vincenot has been a Linux user for eight years, and is currently a student at University Louis Pasteur in Strasbourg.

1.5 Volt AGP Card

2004-08-09T22:53:00.000-07:00

1.5 Volt AGP Card, originally uploaded by Nick00.

This is how the 1.5V (recent) AGP cards look like, they have 3 slots.

non1.5V AGP CArd

2004-08-09T22:51:00.000-07:00

non1.5V AGP CArd, originally uploaded by Nick00.

This is how a non 1.5v (older) AGP card looks like.

exporting ENV Variables

2004-08-04T15:02:00.000-07:00

While setting ENV variables there should be no space between the "=" signs as in the following examples:-

export PATH=$PATH:/usr/X11R6/bin
^^ ..no space this would work

export PATH =$PATH:/usr/X11R6/bin
^ ...space..this would screw up.

Mount

2004-08-02T14:44:00.000-07:00

Let

fs0 : be a file system of type1
fs1: be a file system of type2
$PREFIX: be any directory prefix, like /usr,/home, /home/rajiv/../whatever
temp: be a sub-directory in $PREFIX

If the $PREFIX/temp directory of fs0 contains any files, they are hidden or covered, when fs1 is mounted in it and may no longer be available for use. When fs1 is unmounted, these files become visible once again.

Herez an example....

my temp directory contains..

rajiv@linux:~/temp> ls
total 3.0M
512 docs/ 28K libj2k.tar.gz 3.0M linphone-0.12.2.tar.gz
0 libj2k/ 1.5K linphone-0.12.2/

linux:/home/rajiv/temp # cd ..
## now mount my cdrom on temp ##
linux:/home/rajiv # mount /dev/cdrom temp
mount: block device /dev/cdrom is write-protected, mounting read-only
linux:/home/rajiv # cd temp
linux:/home/rajiv/temp # ls
. .esd_auth .icons .profile trash
.. evolution .java public_html .Trash
.acrobat .exrc .kde .qt .tsclient
.adobe .fonts .kermrc .RealNetworks_RealCookies_60 .urlview
.bash_history .fonts.cache-1 LL .RealNetworks_RealMediaSDK_60 .viminfo
.bashrc .gaim .mailcap .RealNetworks_RealPlayer_60 .weblink
bin .galeon .mcop .RealNetworks_RealShared_00 .wmrc
.BitchX .gconf .mcoprc .recently-used .Xauthority
cheat_sheet.txt .gconfd .metacity rr_moved .xchat2
codes .gnome .mime.types sipTutorial .xcoralrc
.ddd .gnome2 .mozilla .skel .xemacs
Desktop .gnome2_private .muttrc .ssh .xim.template
Documents .gnome-desktop .nautilus staroffice7 .xinitrc.template
downloads .gstreamer .netscape .sversionrc .xmms
.dvipsrc gtk .netscape6 template .xsession-errors
.emacs .gtkrc-1.2-gnome2 notes .themes .xtalkrc
.emacs.d .ICEauthority Old KDE Desktop .thumbnails

##See, the original files are hidden ##

Some Info I need

2004-07-28T20:28:00.000-07:00

via pci 10/100Mb Fast Ethernet Adapter

VIA VT86c100A Rhine-II

Recorder option

Documentation on ALSA

2004-07-26T15:35:00.000-07:00

http://alsa.opensrc.org

Sound, ALSA, Esound etc

2004-07-26T14:36:00.000-07:00

Had been running the box with no sound for a week:-

Herez what had happened

a) I booted the machine one fine day and saw the initial demsg messages report a segmentation error of some sort. The boot process also hung.
b) Being in my morning blues, I simply pressed CTRL+DEL+ALT and restarted the boot process
c) There was nothing untoward in the boot messages.
d) Everything worked fine except .....sound.
e)Checked the Yast2 runtime editors..ALSA was running and ESound was not.
f) Didnt quite understand what to do...
g) stopped and started alsa again..nothing happened.
h) Tried starting esound....but it complained of a --terminate option in /etc/esound configuration
i) read some more abt esound...seemed more like something that would help different applications share/use/multiplex into a common dsp resource.
j) the problem seemed more fundamental...the audio device was not working.
k) downloaded the endoftheworld WAV file from the SOUND HOWTO and did a cat endoftheworld > /dev/dsp
l) nothing happened.
m) ran alsaconf
n) detected my sound cards alrite
o) Asked me if it could rewrite configuration files.
p) i said yes...
q) it said that it would play a test sound ..i said OK..but didnt hear any.
s) It said that the configuration is complete.
t) I fired up totem..and indeed i got sound back!!!!..I have no clue how that happened!!!

Terminal Emulators

2004-07-22T11:36:00.000-07:00

All terminal Emulators are located in ( Suse 9.1):
/usr/X11R6/bin

rajiv@linux:/usr/X11R6/bin> ls | grep term
8.0K Eterm
308K mlterm
8.0K mlterm-zoom
4.0K uxterm
84K wterm
4.0K xfterm
308K xterm
16K xtermset

Sound Card Advanced Options for OnBoard Audio

2004-07-19T00:21:00.000-07:00

sound_advanced, originally uploaded by Nick00.

These are the advanced options for the onboard Audio Controller.

VT8233/A/8235 AC97 Audion Controller
Vendor: Via

Sound Configs

2004-07-19T00:11:00.000-07:00

sound, originally uploaded by Nick00.

YAST->Hardware->Sound yields the Sound Configuration Window.
I disabled the onboard Audio and unchecked the Start sequencer tab.

Big Fat Kernel Loses Weight

2004-07-18T23:59:00.000-07:00

The Runlevel tuneup reduced the number of loaded modules from 58 to 39.
This is what I have..

Module Size Used by
snd_seq_oss 30976 0
snd_pcm_oss 56868 1
snd_mixer_oss 18688 1 snd_pcm_oss
snd_seq_midi 8864 0
snd_seq_midi_event 7680 2 snd_seq_oss,snd_seq_midi
snd_seq 54672 5 snd_seq_oss,snd_seq_midi,snd_seq_midi_event
snd_via82xx 24224 0
snd_mpu401_uart 7808 1 snd_via82xx
snd_ens1371 22368 1
snd_rawmidi 24992 3 snd_seq_midi,snd_mpu401_uart,snd_ens1371
snd_seq_device 8328 4 snd_seq_oss,snd_seq_midi,snd_seq,snd_rawmidi
snd_pcm 96776 3 snd_pcm_oss,snd_via82xx,snd_ens1371
snd_page_alloc 11012 2 snd_via82xx,snd_pcm
snd_timer 25476 2 snd_seq,snd_pcm
snd_ac97_codec 60676 2 snd_via82xx,snd_ens1371
snd 59524 14 snd_seq_oss,snd_pcm_oss,snd_mixer_oss,snd_seq_midi,snd_seq_midi_event,snd_seq,snd_via82xx,snd_mpu401_uart,snd_ens1371,snd_rawmidi,snd_seq_device,snd_pcm,snd_timer,snd_ac97_codec
soundcore 8800 2 snd
gameport 4736 2 snd_via82xx,snd_ens1371
af_packet 20360 0
via_rhine 19720 0
mii 5248 1 via_rhine
ehci_hcd 27140 0
uhci_hcd 29584 0
via_agp 7424 1
agpgart 28712 1 via_agp
usbcore 96988 4 ehci_hcd,uhci_hcd
evdev 9600 0
ipv6 244100 17
binfmt_misc 9992 1
subfs 7296 2
nls_utf8 2176 1
ntfs 86092 1
dm_mod 50044 0
reiserfs 233808 1
sata_via 6916 0
libata 37504 1 sata_via,[permanent]
sd_mod 19840 0
scsi_mod 107980 2 libata,sd_mod

Editing RunLevels Even Further

2004-07-18T23:48:00.000-07:00

hwscan, originally uploaded by Nick00.

Turned off Hardware scan and reconfiguration on boot.

Editing RunLevels Further

2004-07-18T23:30:00.000-07:00

Disabled coldplugging and then rebooted. The network won't come up.

Coldplugging is required for initializing fixed and already plugged devices. My ECS KT600A motherboard has built-in network support. Thats why the poor soul wont boot.

Editing RunLevels

2004-07-18T23:18:00.000-07:00

Shutting down the following services ...
a) CUPS
b) ISDN
c) NFS
d) Hotplugging

that bought down the memory from 194M to 174M ;)

Big Fat Greek Kernel

2004-07-17T22:33:00.000-07:00

58 modules :(, originally uploaded by Nick00.

With the following specs... my memory foot-print was a whopping 390 Megs
a) linux 2.6.4-52-default
b) Gnome 2.4
c) Tons of applets and a polished desktop
d) Only 512MB of RAM :(

A quick lsmod revealed 58 modules.See my next / prev post.Thats way too much! . A good thing about that these modules is that /usr/src/linux/Documentation has a good documentation of most/each of these. Herez a cat-ed output of my lsmod...

Module Size Used by
usbserial 28912 0
parport_pc 35264 1
lp 10916 0
parport 37704 2 parport_pc,lp
edd 9240 0
joydev 10176 0
st 38940 0
sr_mod 15652 0
ide_cd 36484 0
cdrom 36508 2 sr_mod,ide_cd
nvram 8328 0
snd_seq_oss 30976 0
snd_pcm_oss 56868 1
snd_mixer_oss 18688 3 snd_pcm_oss
snd_seq_midi 8864 0
snd_seq_midi_event 7680 2 snd_seq_oss,snd_seq_midi
snd_seq 54672 5 snd_seq_oss,snd_seq_midi,snd_seq_midi_event
speedstep_lib 3712 0
snd_via82xx 24224 1
snd_mpu401_uart 7808 1 snd_via82xx
freq_table 4612 0
thermal 12424 0
processor 16040 1 thermal
fan 3972 0
button 6032 0
battery 8580 0
ac 4868 0
snd_ens1371 22368 2
snd_rawmidi 24992 3 snd_seq_midi,snd_mpu401_uart,snd_ens1371
snd_seq_device 8328 4 snd_seq_oss,snd_seq_midi,snd_seq,snd_rawmidi
snd_pcm 96776 3 snd_pcm_oss,snd_via82xx,snd_ens1371
snd_page_alloc 11012 2 snd_via82xx,snd_pcm
snd_timer 25476 2 snd_seq,snd_pcm
snd_ac97_codec 60676 2 snd_via82xx,snd_ens1371
snd 59524 14 snd_seq_oss,snd_pcm_oss,snd_mixer_oss,snd_seq_midi,snd_seq_midi_event,snd_seq,snd_via82xx,snd_mpu401_uart,snd_ens1371,snd_rawmidi,snd_seq_device,snd_pcm,snd_timer,snd_ac97_codec
soundcore 8800 4 snd
gameport 4736 2 snd_via82xx,snd_ens1371
af_packet 20360 0
ehci_hcd 27140 0
via_rhine 19720 0
mii 5248 1 via_rhine
uhci_hcd 29584 0
usbcore 96988 5 usbserial,ehci_hcd,uhci_hcd
via_agp 7424 1
agpgart 28712 1 via_agp
evdev 9600 0
ipv6 244100 13
binfmt_misc 9992 1
subfs 7296 2
nls_utf8 2176 1
ntfs 86092 1
dm_mod 50044 0
reiserfs 233808 1
sata_via 6916 0
libata 37504 1 sata_via,[permanent]
sd_mod 19840 0
scsi_mod 107980 4 st,sr_mod,libata,sd_mod

My First Successful Mozilla Build!!!

2004-07-16T13:11:00.000-07:00

First Successful Build of Mozilla, originally uploaded by Nick00.

Building the Lizard!

2004-07-15T23:41:00.000-07:00

This is a screen shot of a Mozilla Build in progress.

Hints and Tips

1)If you just want to pull the tree,

gmake -f client.mk checkout

Screenshot
Originally uploaded by Nick00.

libIDL-config script

2004-07-15T23:21:00.000-07:00

The ./configure process ( see previous post) complained about not finding libIDL-config script. Also LIBIDL_CONFIG was ""
I did a
rajiv@linux:~> locate libIDL
/opt/gnome/bin/libIDL-config-2
/opt/gnome/include/libIDL-2.0
/opt/gnome/include/libIDL-2.0/libIDL
/opt/gnome/include/libIDL-2.0/libIDL/IDL.h
---snipped---
I updated LIBIDL_CONFIG to /opt/gnome/bin/..thats where libIDL-config-2 was located.

ran ./configure...still the same problem..

I then copied libIDL-config-2 as libIDL-config

ran ./configure....and woot! it ran to completion...

GTK_CONFIG variable, gtk-config script

2004-07-15T23:11:00.000-07:00

Was building Mozilla....
./configure complained abt not finding gtk-config script anywhere.
Used Yast2 to find out what gtk packages are installed.
Saw some developer packages where not installed.
Installed...ran fine....:)

Environment Variables in Bash

2004-07-15T23:04:00.000-07:00

To make lasting changes to the value of an environment variable:

1. Use your editor to open the .bash_profile file and add the line:

   VARNAME=value_of_variable;export VARNAME

2. Save the file and leave the editor.

3. Enter the command:

   source $HOME/.bash_profile

This adds the new value to your working environment.

Here is a Copy of my .bash_profile. I created it . It wasnt there by default when I installed Suse9.1

#Start

CVSROOT=:pserver:anonymous@cvs-mirror.mozilla.org:/cvsroot;
export CVSROOT;

#EOF

Writing CDs

2004-07-04T08:56:00.000-07:00

Step 1 : Creating a iso image of the data to be burnt

mkisofs -r -o home_dir_image_to_be_burnt ~rajiv/

Step2: Verifying the isoimge

i) su
ii) mkdir /cdrom
iii) mount -t iso9660 -o ro,loop=/dev/loop0 home_dir_image_to_be_burnt /cdrom

Step3: cd to /cdrom and verify the file structure

Step4: Finding out which SCSI device the CD Writer is attached to

cdrecord -scanbus

Step5: Writing the actual CD

cdrecord -v speed=2 dev=0,0,0 -data home_dir_image_to_be_burnt