“It’s A Brick” – Tesla Motors’ Devastating Design Problem

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“It’s A Brick” – Tesla Motors’ Devastating Design Problem

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Don’t jump on the Tesla bandwagon JUST yet — http://theunderstatement.com/post/18030062041/its-a-brick-tesla-motors-devastating-design

Very Good Article on Linux Services

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How To Install Services on Linux

Allow me to give you a little introduction on the subject prior to the proper howto. The Linux boot process can be split up in three steps:

  • Loading the kernel
  • Device detection and configuration
  • Granting control to ‘init’

The ‘init’ program is a daemon that spawns all other processes in the system. It is responsibe for loading the system using initialization scripts, which are usually found at /etc/init.d. There are two ways for init to operate, BSD and SystemV. Typically, Linux systems use SystemV, though there are distributions like Arch Linux or Slackware that use BSD.

The runlevel is a number used to identify the mode in which the computer is. For example, a runlevel 0 would mean that the computer is halted, while changing the runlevel to 6 would make the computer reboot. There are 7 runlevels. Runlevels from 1 to 5 usually differ in the programs that are automatically started. Typically, runlevel 3 is used to boot in text-only mode, while runlevel 5 will start the X server and the desktop environment.

For each runlevel, there is a folder named rcN.d (where N stands for the runlevel number) which contains symbolic links to the some of the scripts located at /etc/init.d.

When changing the runlevel, what the system does is:

  • Changing directory to /etc/rcN.d or /etc/rc.d/rcN.d (depends on the distribution).
  • All the scripts that begin with K are executed in alphabetical order with the argument ‘stop’. Usually there are numbers after the K to be able to control the exact execution order.
  • All the scripts that begin with S are executed in alphabetical order with the argument ‘start’. As before, numbers are used to sort the scripts before execution.

If you want to learn more, you can find information about init and runlevels at:

http://en.wikipedia.org/wiki/Init
http://en.wikipedia.org/wiki/Runlevel
http://www.redhat.com/docs/manuals/linux/RHL-7.2-Manual/ref-guide/s1-init-boot-shutdown-init.html
http://linux.about.com/od/commands/l/blcmdl8_init.htm


Now lets get our hands dirty and learn how to make the BitNami stack servers start at boot time 🙂 Bear into mind that you will need root privileges to do it.


Debian-like distribution (Debian, Ubuntu, etc)

1. Copy the installdir/ctlscript.sh file to /etc/init.d . It is advisable to rename this script to something more specific, like “bitnami-drupal”.

cp ${installdir}/ctlscript.sh /etc/init.d/bitnami-drupal


2. We will use rc-update.d to add the script to the desired runlevels.

update-rc.d -f bitnami-drupal start 80 2 3 4 5 . stop 30 0 1 6 .

As you can see, we define the priority (80 for start and 30 for stop) and the runlevels in which the script will be executed. The result of this command will be something like

Adding system startup for /etc/init.d/bitnami-drupal ... /etc/rc0.d/K30bitnami-bitnami-drupal -> ../init.d/drupal /etc/rc1.d/K30bitnami-bitnami-drupal -> ../init.d/drupal /etc/rc6.d/K30bitnami-drupal -> ../init.d/bitnami-drupal /etc/rc2.d/S80bitnami-drupal -> ../init.d/bitnami-drupal /etc/rc3.d/S80bitnami-drupal -> ../init.d/bitnami-drupal /etc/rc4.d/S80bitnami-drupal -> ../init.d/bitnami-drupal /etc/rc5.d/S80bitnami-drupal -> ../init.d/bitnami-drupal


And that’s it, the servers will be loaded at boot time. To revert the changes, just type

update-rc.d -f bitnami-drupal remove

RedHat-like distribution (Red Hat, Fedora Core, CentOS, Suse, etc)

1. Copy the installdir/ctlscript.sh file to /etc/init.d . It is advisable to rename this script to something more specific, like “bitnami-drupal”.

cp ${installdir}/ctlscript.sh /etc/init.d/bitnami-drupal

2. You have to modify the script a little bit to make it work at boot time. Just add the following lines at the beginning of the file

#!/bin/sh # # chkconfig: 2345 80 30 # description: BitNami Service


This means that the script will be executed in runlevels 2, 3, 4 and 5, with priority 80 to start, and 30 to stop.


3. Now, you only need chkconfig to install the script as a service.

chkconfig --add bitnami-drupal

And you’re done. To revert the changes, we will use chkconfig again

chkconfig --delete bitnami-drupal

That’s all! If you have comments or suggestions, please post at the following topic on the forums

http://bitnami.org/forums/forums/27/topics/344

some frightening numbers

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some frightening numbers

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