beardy's

If a PDP-8 minicomputer can’t help with Greece, who can?

beardy — Mon, 26 Sep 2011 02:38:06 +0000

.BASIC NEW OR OLD--OLD FILE NAME--HELLO.BA

READY
RUN

HELLO BA 5A

HELLO, MY NAME IS PETEY P. EIGHT.

WHAT’S YOUR NAME ?BEARDY

HI THERE BEARDY. ARE YOU ENJOYING YOURSELF HERE
IN THIS WONDERFUL PLACE?YES

OH, I’M GLAD TO HEAR THAT BEARDY

SAY, BEARDY, I CAN SOLVE ALL KINDS OF PROBLEMS
EXCEPT THOSE DEALING WITH GREECE. WHAT KIND OF
PROBLEMS DO YOU HAVE (ANSWER SEX, HEALTH, MONEY,
OR JOB)?

Not even a DEC PDP-8 (simulated in SIMH) running OS/8 and a BASIC program, HELLO.BA, can help with Greece!

Guess if I dropped my jaw in surprise and amusement when I read that, when playing around with a simulated historic computer just now. If not even that can help to solve the problems of/with Greece, I guess they’re doomed!

On another note, SIMH is a great thing, the DEC PDP-8 minicomputer (from 1965) seems to have been a nice machine in its days, and OS/8 quite a decent OS for its time and environment. Expect another post on SIMH and simulating/emulating old computers shortly.

Cron, crontab example reference and how to run things periodically in GNU/Linux and Unix

beardy — Thu, 04 Nov 2010 18:54:56 +0000

Cron is a job scheduler found in most Unix-like operating systems. “Chronos”, which is the Greek word for “time”, is where the name cron comes from. Cron makes it possible to schedule jobs, which can be commands, a series of commands, or scripts, that you want to run periodically. Common uses are backups, notifications, periodic checks on availability of services, networks, machines, or other things, and administration and maintenance tasks like rotating of logs, to mention a few. It is very general-purpose though, (like Unix tools is and should be) and can be used for whatever you can think of that needs to run periodically.

Jobs that should be run by cron are specified in crontab (cron table) files. A crontab is a configuration file that specifies commands (shell commands, including programs, scripts, or pipelines thereof) to be run, and when they should be executed.

Each line in a crontab file represents a “job”, and is composed of a CRON expression (specifying the time) followed by the command or commands to be executed. There are two different crontab files, the ones installed by system software, and editable only by root (but in most cases best left alone), and crontab files written by and belonging to users (including root). The authorization control to cron, who will be allowed to have a crontab or not, are done with the files /etc/cron.allow and /etc/cron.deny.

The manpages of cron and the crontab format are nice. “crontab” is both the name of the program installing, listing and editing user’s crontabs, and the file format manpage, so do read them:

man cron
man 1 crontab
man 5 crontab

The page in section 5, about the format is most interesting. However I prefer to keep a short reference in my user’s crontab file itself for quick reference, feel free to grab it:

# mycrontab.txt
# beardy
# My example crontab, kept in ~/

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

# Send the mail to another address than the local user
##MAILTO=foo@foo.bar

##############################################################################
#
# The following example should run "true" every day of every month, at half
# past eight, every day of the week.
#
# Example:
#
# 30 8  * * *   true
# |  |  | | |    |
# |  |  | | |    +--- command, or script, to run
# |  |  | | +-------- day of week, 0-7 or mon, Tue, FRI
# |  |  | +---------- month, 1-12, or names, jan, Mar, AUG (case doesn't matter)
# |  |  +------------ date, 1-31
# |  +--------------- hour, 0-23
# +------------------ minute, 0-59
#
# see "man 5 crontab"
#
#     Instead of the first five fields, one of eight special strings may
#     appear:
#
#           string          meaning
#           ------          -------
#           @reboot         Run once, at startup.
#           @yearly         Run once a year, "0 0 1 1 *".
#           @annually       (same as @yearly)
#           @monthly        Run once a month, "0 0 1 * *".
#           @weekly         Run once a week, "0 0 * * 0".
#           @daily          Run once a day, "0 0 * * *".
#           @midnight       (same as @daily)
#           @hourly         Run once an hour, "0 * * * *".
#
##############################################################################

# Run beep every Christmas Eve, at 14:40 (20 min before Kalle Anka)
#40 14  24 12 * beep -f 1000 -r 5 -l 150 -D 250
# next job goes after this line
40 14   24 12 * echo "God Jul!"

To install a new crontab, the crontab(1) program is used:

crontab mycrontab.txt

To later list it, and edit it (with the editor configured with the $EDITOR environment variable usually):

crontab -l
crontab -e

Fixing missing menu entries of Opera and Skype in Debian GNU/Linux

beardy — Wed, 20 Oct 2010 05:48:37 +0000

Unfortunately the third-party packages of Opera and Skype do not contain menu entries for the Debian menu system. Not very surprisingly one might think, but I just think it’s sloppy. If you, like me, like the Debian menu system and want Opera and Skype available in it, do the following to solve that, until the packagers have included the menu entry files themselves:

(Update: I noticed that Opera has apparently had a menu entry in its package before, but has now removed it. It’s explained in this post, but I still think that was a bad choice.)

To override, or in this case add menufiles in Debian, one should put the files in /etc/menu. Put the following in /etc/menu/opera:

?package(opera):needs="x11" section="Applications/Network/Web Browsing" \
  title="Opera" command="/usr/bin/opera" hints="Web browsers" \
  icon="/usr/share/icons/hicolor/32x32/apps/opera-browser.xpm"

And the following in /etc/menu/skype:

?package(skype):needs="X11" section="Applications/Network/Communication" \
        title="Skype" \
        longtitle="Skype" \
        icon="" \
        command="skype"

Then run ‘update-menus‘ after you have added the above files to update the menu system, and have Opera and Skype available in your window manager’s menus.

Modems & Bulletin Boards, The Computer Chronicles

beardy — Sun, 10 Oct 2010 22:27:07 +0000

This Sunday’s video (I will from now on try to post atleast one video from this series, or another, each Sunday (even though it technically is Monday in this part of the world)) is about modems and bulletin boards (BBS:es). I also have to recommend the movie/series ”BBS: The Documentary“ which is very interesting and well made.

From high-tech trysts to selling black-market software, computers users are talking.

Guests: Ezra Shapiro, Byte Magazine; Rory O’Connor, InforWorld; Matthew McClure, The Well; Donald Ingrim, Alameda County DA; George Morrow, Morrow Computing

Products/Demos: CompuServe, Byte BBS, The Well

Let’s hear your thoughts and comments after watching the video, enjoy.

3 WordPress plugins

beardy — Sat, 09 Oct 2010 19:22:06 +0000

Advanced Permalinks dashboard screenshot

Yesterday I decided to change the permalinks structure of this site. I wondered if WordPress had redirection built into to the core, but it seems it does not yet. But there are many plugins, like always, providing the needed functionlity. At first I looked at one called Redirection, but it was not really what I was after. If seems to do most things one could want regarding redirects and 404 logging, but I only wanted to simply redirect my old “YYYY/MM/DD/postname” structure to “/postname”. I then tried another plugin called Advanced Permalinks, which does exactly what I wanted. After installing it, its options/functionality is found under Settings->Permalinks->Migration in the WordPress administration dashboard.

This allows you to move from one permalink structure to another one, and have the old structure be forwarded to the new, for each post. I used the “/%year%/%monthnum%/%day%/%postname%/” structure before, but I switched to the “/%postname%/” structure. Now, with the Advanced Permalinks plugin my possible old links in to my articles are forwarded properly.

The second plugin I installed and tried yesterday was Optimize DB, a simple plugin that just does what the name says, optimizes the MySQL database with one click. Seems to do its work well too. For my little site it wasn’t that much to optimize, but a few kilobytes atleast.

The third plugin I installed, and which you can see the effects of in this post, is Lightbox Plus, which handles the viewing of images fullsize in an overlay frame using javascript, instead of opening the image directly. Click on the image in this post and see.

Are you using any of these plugins and have anything to add? leave a comment.

Restaurang Emanuel lägger ner verksamheten

beardy — Fri, 18 Jun 2010 13:46:30 +0000

Eftersom de själva, på sin egen webplats, http://restaurangemanuel.com/ endast har lagt ut ett Microsoft Word-dokument, tänkte jag att någon bör ge det hela lite mer uppmärksamhet. Restaurang Emanuel ligger (eller väldigt snart låg) i huset där jag bor. Jag har ätit där några gånger såklart, maten är bra. Fastigheten har haft ett antal olika ägare under tiden jag har bott här, den nuvarande har tydligen bestämt sig för att bete sig ganska underligt, och restaurangen lägger nu ner sin verksamhet.

Nedan följer restaurangens information som de som sagt endast tillgängliggjort i ett dåligt format. Hoppas de inte misstycker att jag publicerar det här.

Restaurang Emanuel i graven

Ja, efter 20 år i branschen så lägger Restaurang Emanuel ner verksamheten.

Vi vill gärna berätta lite om bakgrunden till det hela.
Av någon outgrundlig anledning, så var vår första personliga kontakt med hyresvärden, i form av en delgivningsman.
För några månader sedan klev en man in i köket. Han såg ut att vara klippt ur en gangsterfilm och kom alltså från en delgivningsbyrå.
Han överlämnade en bunt papper som vi uppmanades att skriva på.
Utan minsta förvarning, kontakt eller diskussion från hyresvärden, levererade han en uppsägning av vårt hyreskontrakt samt lämnade ett nytt.
Senare fick vi reda på att den ”charmige” delgivaren, hade varit hos andra privata hyresgäster i liknande ärenden, samma dag.

Restaurang Emanuel består av en stor matsal som byggdes för 20 år sedan.
Köket, som ligger en bit bort är också megastort med en urtida källare till. Orsaken till den stora ytan är så klart att vi huserar i det gamla lasarettsköket, som byggdes på 60-talet. Köket är rejält nedgånget och inte underhållet på de sista 20 åren. Maskinparken är mer än uttjänad.

Det ultimata för en krögare måste vara att ha ett välplanerat, lagom stort och fräscht kök.
I vårt fall är det alltså tvärtom med massor av yta, långt från matsal och med ett stort renoveringsbehov.
Detta, var en gång i tiden bakgrunden till att vi kompenserades med en human hyra.
Våra vänner på Hälsa- och Miljöförvaltningen, tycker inte heller att vårt kök duger.
De har näst intill dömt ut det och vill ha en totalrenovering. Denna ombyggnad vill inte hyresvärden stå för och vi förstår att det är en av orsakerna till det nya kontraktet.

Det nya hyreskontraktet innebär att värden har korrigerat ytan och marknadsanpassat den.
Det resulterar i att hyran höjs nästan fyra gånger, ex tillägg. En så mycket högre hyra, kan våra intäkter inte täcka..Hyran sänktes något, efter det att en representant från hyresvärden kom hit och med egna ögon fick se hur det såg ut i verkligheten.
I det nya kontraktet står bla att vi måste bekosta reparationer, underhåll och förnyelse av samtliga ytskikt, ledningar och utrustning. Fönster måste bytas, golvet kaklas om, nya brunnar behövs, kylar och frysar måste repareras för att bara nämna en bråkdel. Det handlar om renovering i mångmiljonklassen, utöver hyran.
Vi måste även betala elen och det är väl inte så konstigt i sig, i alla fall inte om vi hade haft ett renoverat, litet kök. I denna stora, otäta lokal och med en maskinpark från stenåldern så är den kostnaden enorm.
I det nya kontraktet åläggs vi att själva ansvara och bekosta de åtgärder, som olika myndigheter som tex miljö- och hälsoskyddsnämnd, brandmyndigheten, försäkringsbolag eller annan myndighet kräver.
Vi förstod ganska direkt att vi inte är önskvärda i huset.
Vi har inte en chans att driva en lunchrestaurang under dessa premisser. Speciellt inte när våra
kunder flyttar härifrån, som tex de härliga ungdomarna på folkuniversitetet nu gör.

Kanske vill man istället få in en hyresgäst med mycket, mycket större plånbok eller kanske ska de bygga fler små, trevliga lägenheter där i stället?

En vecka efter besöket från vår mysige delgivningsman, fick vi höra ett rykte om vem som skulle husera i köket efter oss…

Det ska bli mycket intressant att se utvecklingen och vi är övertygade att allt kommer att lösa sig till det bästa.
Värre är det för oss som arbetar på Restaurang Emanuel.
Det har varit mycket mer än ett arbete, mer som en livsstil med mycket slit, skratt och gråt. Det kommer att bli oerhört tomt, sorgligt och arbetslöst.

Nu på fredag 18/6 serverar vi vår sista lunch

Vi vill tacka alla våra underbara gäster och leverantörer under dessa händelserika 20 år.

Ät och lev väl!

Restaurang Emanuel

Om det nu inte finns några andra planer för lokalerna tycker jag det är otroligt korkat från fastighetsägarens sida. Att låta lokaler stå tomma istället för att iallafall täcka en del av kostnaderna och låta verksamhet bedrivas. Nåväl, det återstår att se vad som händer där i framtiden, tråkigt är det i vilket fall som helst.

Se också dessa artiklar från den lokala tidningen:

A revised opinion on apache2-mpm-prefork and apache2-mpm-worker, and php5 and php5-cgi on Debian, regarding performance

beardy — Thu, 17 Jun 2010 19:47:08 +0000

It’s now over a year since I wrote about “Exchanging apache2-mpm-prefork for apache2-mpm-worker, and using php5-cgi on Debian to improve performance“. Since then I have re-evaluated my opinion about running apache2-mpm-worker and php5-cgi on a low memory machine, specifically a virtual machine running under Xen, running Debian.

There are some seemingly positive things with apache-mpm-worker and php5-cgi:

At little to no web traffic load:

fast response time
low memory usage

When traffic load is low (none or few people visiting your sites) the memory usage is very low when using apache2-mpm-worker. This is of course because it doesn’t have the php-interpreter loaded as a module, but also because of other things. When a dynamic site is accessed, and php5-cgi is launched to process your php scripts, it gets done quite fast if there just is enough memory for the process.

Here we come to the biggest problem with this though; when there is a little more visitors, to dynamic content, php5-cgi processes are spawned too fast, and does not have time to finish, more and more memory, and swap, are being allocated, until the webserver goes on its knees, and ends up killing off the php5-cgi processes, or you have to manually kill them, which will drop any connections, from possibly search engines. If you are unlucky you can not even type the kill command in, or atleast have to wait 5 to 10 minutes for it to show up, and execute.

This might be controllable if you configure Apache to run very, very few threads, in mpm-worker, but.. then one is really better off using mpm-prefork, it gives you much harder and better control over how many processes, and visitors, that can be served simultaneously.

I recently switched back to mpm-prefork instead, and pulled down the number of simultaneous connections being served drastically. This probably has the effect of all my sites running “slower”, in the appearance to my visitors, but, it is only slow, even if it is to everyone, atleast it doesn’t drop connections, and completely renders my webserver unusable, at higher visitor loads.

The difference between mpm-worker and mpm-prefork is that mpm-prefork waits until the php-script has been processed, if using the php module that is, which is the most common, while mpm-worker answers the request, then forks off to php5-cgi, and answers another request. I think that is what it does, even if you have the number of threads set very low. It does not wait for php5-cgi to finish no matter what you do. In a low-memory situation, this is bad. I thought it was an advantage to use mpm-worker before, now I do not.

Like I’ve stated in my earlier post, getting more memory really is the only good solution, but again.. this makes me survuve a little longer with this. Below is my current configuration. Feel free to comment and let me know your opinion or experience of simillar situations.

# prefork MPM
# StartServers: number of server processes to start
# MinSpareServers: minimum number of server processes which are kept spare
# MaxSpareServers: maximum number of server processes which are kept spare
# MaxClients: maximum number of server processes allowed to start
# MaxRequestsPerChild: maximum number of requests a server process serves
#
    # beardy, default 5
    StartServers          1
    # beardy, default 5
    MinSpareServers       2
    # beardy, default 10
    MaxSpareServers       3
    # beardy, was 150
    MaxClients            6
    # beardy, was 0
    MaxRequestsPerChild   4000
#

This is only my experience, and your mileage may vary. But I have dealt with this for over a year now, and I think that gives my opinion atleast some substance. As you can see above, I only serve a very, very low amount of visitors simultaneously, but like I said, atleast everyone gets served, if they have a little patience, instead of having every request crawl to a halt, and then get killed. Foremost, search engines are not dropped. (Some crawlers have a high impact occassionally. This is very notable if one uses WordPress for instance, and crawlers pick up new content quickly.)

Since there seems to be some readers of my previous post on this topic, I wanted to share this revised (and current) view as well.

Exchanging apache2-mpm-prefork for apache2-mpm-worker, and using php5-cgi on Debian to improve performance

Other writings and opinions by other people on this subject:

http://www.camelrichard.org/apache-prefork-vs-worker

http://dev.esl.eu/blog/2009/02/12/apache2-mpm-worker-vs-mpm-prefork/

http://articles.slicehost.com/2010/5/20/configuring-the-apache-mpm-on-debian

Slowdown in Silicon Valley #2, The Computer Chronicles

beardy — Mon, 14 Jun 2010 16:12:55 +0000

Part two of this special series looking at the causes of the downturn in the computer industry.

Guests: Ben Anixter, AMD; Richard O’Brien, Hewlett Packard; Trip Hawkins, Electronic Arts; John Merson, Ashton-Tate; Gary Kildall, Digital Research

Products/Demos: Commodore Amiga, Atari ST 520

Enjoy this video from 1985, this is part two of a two part episode of Computer Chronicles.

Slowdown in Silicon Valley #1, The Computer Chronicles

beardy — Mon, 14 Jun 2010 12:12:00 +0000

A review of the reasons behind the current slump in the computer business.

Guests: Dave Crockett, Dataquest; Sam Colella, Inst Venture Partners; Deborah Wise, Business Week; Dave Norman, Businessland; Gary Kildall, Digital Research

Products/Demos: Adam Computer, Osborne I Computer

Enjoy this video from 1985, this is part one of a two part episode of Computer Chronicles. Feel free to discuss it below.

UNIX, The Computer Chronicles

beardy — Sun, 13 Jun 2010 12:13:48 +0000

This is a very interesting episode, if you watch it, you can often draw paralells to todays reality, and can think back on what actually happened, and how long it has taken for some things. The interesting thing with many, and in particular this episode of Computer Chronicles, is that it could have been recorded last week, and still felt like a good report of current events. (Though of course some names needs changing, some screenshots would be flashier.. but the overall content and facts could be the same.) Like always when watching these videos I think; “Nothing changes, things change slowly, things move in circles, nothing is new under the sun.”

I just watched this video again, and had to add the above comment to it. Enjoy watching the video, for the first time, or again, and again. 2011-08-13 update

AT&T’s computer operating system is threatening to take over IBM’s MS-DOS dominance.

Guests: John Mashey, Bell Labs; Mark Sobell, Author; Bill Joy, Sun Microsystems; Doug Hartman, Hewlett Packard; Mike Denney, Basis; Gary Kildall, DRI

Products/Demos: File It, HP Integral PC, UNIX

Enjoy this video, from 1985.