Camstreams and lftp

In my last post I alluded to a web-cam project I was working on. I had hoped the software I was using for Linux, Camstream, was capable of uploading to me site, and there appeared to be facilities to do so - the only problem was that all the images it uploaded had a zero-byte size; in other words the upload didn't work properly. Luckily, Camstream did save the image perfectly to the hard drive, which meant I could use a little scripting to auto upload it to my web site.

I'm no hard core shell script hacker, this is just my solution to a problem; I'm sure there are plenty of better solutions, but this one works for me, so I thought I would share:

First I needed to find a ftp program that I could script. I chose lftp because it seemed like the easiest program to script, you just run lftp with the -f switch and the name of your script. For example, if your script is called uploadimage you'd get cron to run:

/usr/bin/lftp -f /home/username/uploadimage

Where /home/username is the path to where you put your script. The second job was to write a script that would upload the image. This was actually just a few lines of script:


open -u myusername,mypassword my.ftp.server.address
rm /img/videocamera.jpg
put -c -O /img /home/myusername/videocamera.jpg
quit


It's a very simple script. The first line connects to the ftp server at my.ftp.server.address. Line 2 removes the existing image. Line 3 puts the new image with a switch to overwrite the old image if it exists. And the last line ensures lftp quits.

I tested the script before putting it in a cron job by typing:

lftp -f /home/myusername/uploadimage

When it worked I put the script into a cron job:

0,5,10,15,20,25,30,35,40,45,50,55 * * * * /usr/bin/lftp -f /home/myusername/uploadimage

The 0,5,10,15... part ensures the cron job runs every 5 minutes. The other four stars ensures the job runs every day of the week. Now, I probably should have mentioned how to edit a cron job in the last post, and before I posted the line above, but it's been a long day and I'm still trying to wind down, so here it is: as root type:

crontab -u myusername -e

Substitute the user name you use on your local Linux system, not the username you would use on your ftp site.

The last element was creating a simple html page to display the image videocamera.jpg. I won't explain the mechanics of HTML here, but I'll mention that I borrowed some javascript code, and hacked it to refresh the web page itself about every 3 minutes.

Resources:

• My camera feed
  
• Camstream
  
• lftp
  

Please note that if the camera feed is black it's probably dark out, or I'm chilling watching a movie. I still have a way to go with this project and will probably run the images through imagemagick, but that's another post...

Scripts and cron jobs

My first "real" computer was an IBM PC/XT. While our family had a Commodore 64, I don't think anyone would argue that it was anything but a game machine, at least not the way we used it. Since the XT was my introduction to the Personal Computer market, I got pretty use to IBM and Microsoft DOS (Disk Operating System).

I've never been much of a code hacker/junkie, but I did slap together quite a few batch files to get DOS to save me a few steps. Under Linux you can also script things. Most scripts begin by pointing to whatever shell you're using. I would imagine that a good 60% of the Linux community is using good old Bash. An example bash script:

#!/bin/bash

echo "Shell scripting is fun"

Then you would change permissions on the script to include execute permission, at least for yourself. Be wary of arbitrarily running shell scripts which you don't know the purpose of - you don't want to run a rootkit.

chmod ug+x myshellscript

Now the user who created myshellscript has permission to run it, as does anyone who belongs to the same group as the user.

So what good is all this? When combined with another tool, cron, you can schedule your script to run at certain intervals. I've set up a cron job that runs a script which connects to a ftp server and uploads a web cam image at certain intervals.

I won't go into the details of cron because this post is long enough, but the links below should help.

Resources:

• IBM PC XT

  
  

• IBM DOS

  
  

• MS DOS

  
  

• Bash Programming Introduction HOWTO

  
  

• Newbie Intro to Cron

  
  

Cheers until next time!

UltraSparc T1

Sun Microsystems has unveiled a new processor in its UltraSparc line of processors, the UltraSparc T1, codename Niagara. The chip boasts 8 "computing engines" and according to an article on ABC News, uses about half the power of traditional processors.

I hope this improves sales of Sun machines. I'd like to see Sun stick around. Sun has made some pretty sweet machines, and it's nice to have an alternative to the Intel/AMD architecture, even if the machines are a little expensive.

Go Sun, go!

Resources:

• Sun Microsystems - Overview of the UltraSparc T1
  
• ABC News article - Sun Unveils New Server Chip
  

Ultra 2 almost $60k!

I came across a review on Sunworld of the Ultra 1 and 2. I was surprised to see that it was close to $60,000 originally!

The Ultra 2 Creator 3D 2200 comes with a pair of 200-MHz UltraSPARC CPUs, 256 megabytes of RAM, a 4 gigabyte hard disk, and 20-inch monitor. It costs $59,995. With a multi-threading, multi-processing SunSoft compilers, the Ultra 2 generates 332 SPECint92 and 505 SPECfp92, the highest recorded floating-point SPEC92 results.

It sounds like I may have got even more of a bargain than I thought!

Resources:

• Sunworld article