Posts Tagged Linux

Remove DOS carriage return

After writing a shell script on Windows and trying to execute it on Linux, I got the following error message:

/bin/sh^M: bad interpreter: No such file or directory

The problem is obviously because the return line character on Windows and Linux are different. But how to fix it in order to execute it on Linux?
I firstly tried to open it, copy the content of the file and paste it in a new file using only Linux command line, but it didn’t work. :(

However, I found the following thread which fixed the problem:
http://www.reachdba.com/showthread.php?335-bin-sh-M-bad-interpreter-No-such-file-or-directory-apps11i-Instalation

Here is what you need to do:

  1. Open your file using vi
  2. Write the command :set fileformat=unix
  3. Save the file using :wq

The file should now run on Linux. :)

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CP2102 on DNS-323

In one of my personal projects, I needed to connect and use a USB to RS232 (Serial) converter on my D-Link DNS-323. Weird requirements, I know. Anyway… :-|
Plenty of these converters exist out there, but I choose to go for a CP2102:

Innocently, I first tried to compile the code source of this module which can be found on the following page:
http://www.silabs.com/products/mcu/Pages/USBtoUARTBridgeVCPDrivers.aspx

After a few painful and unsuccessful tries, I decided to look around for the already-compiled module. ;)
While wondering why I didn’t think of that before, I used the instructions below to install the required modules on my NAS:

cd /mnt/HD_a2/ffp/lib/
mkdir modules
mkdir modules/2.6.12.6-arm1
cd modules/2.6.12.6-arm1
wget http://dev.skcserver.de/dns323/modules_v1.03/kernel/drivers/usb/serial/usbserial.ko
wget http://dev.skcserver.de/dns323/modules_v1.03/kernel/drivers/usb/serial/cp2101.ko
chmod 755 usbserial.ko
chmod 755 cp2101.ko


Once the modules are installed, the next step is to initialize them.
I wrote the following script for this purpose so you can execute it anytime you need it:

#!/bin/sh

insmod /ffp/lib/modules/2.6.12.6-arm1/usbserial.ko
insmod /ffp/lib/modules/2.6.12.6-arm1/cp2101.ko
mknod /dev/ttyUSB0 c 188 0
chmod 0666 /dev/ttyUSB0


At this point in time, you should have your module initialized on your D-Link DNS-323.
You can check the kernel ring buffer using the dmesg command to verify it loaded properly.
This is a snapshot of what I have in my kernel ring buffer after I ran the script above:

usbcore: registered new driver usbserial
drivers/usb/serial/usb-serial.c: USB Serial support registered for Generic
usbcore: registered new driver usbserial_generic
drivers/usb/serial/usb-serial.c: USB Serial Driver core v2.0
drivers/usb/serial/usb-serial.c: USB Serial support registered for CP2101
CP2101 1-1:1.0: CP2101 converter detected
usb 1-1: reset full speed USB device using ehci_platform and address 5
usb 1-1: CP2101 converter now attached to ttyUSB0
usbcore: registered new driver CP2101
drivers/usb/serial/cp2101.c: Silicon Labs CP2101/CP2102 RS232 serial adaptor driver v0.04


Finally, you can test the communication with your USB to RS232 converter by connecting a LED between the RXD and 3V outputs and running the following script:

#!/bin/sh

while [ true ]
do
echo "hello world!!!" > /dev/ttyUSB0
echo "sent"
sleep 1
done

If you see the LED blinking, it means you succeed! :D

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Ubuntu on Mac Mini PowerPC

The other day, I got an old Mac Mini PowerPC from 2005. And I decided to install Linux on it instead of using an old version of Mac OSX. Fun, ins’t it?

The first thing I did was to download the ISO image of the last version of Ubuntu and burn it on CD. But unfortunately, I discovered that the CD player wasn’t working anymore. :-|
I then tried to put Ubuntu on a USB key and boot on it. But it didn’t work either… This machine didn’t seem to be able to boot from a USB stick.

So how am I going to install Linux without a CD player and USB?
FireWire? Maybe, but I don’t have anything on FireWire.
The answer is netboot! :D Indeed, my last chance was to install it via netboot.

Here are the steps I followed:

  1. Install tftp on another Linux machine in your local network
  2. Configure tftp. Please find below the configuration file I used:
    #
    # ftp://ftp.kernel.org/pub/software/network/tftp/
    #
    service tftp
    {
           flags            = REUSE
           socket_type      = dgram
           protocol         = udp
           instances        = 30
           wait             = yes
           user             = root
           server           = /opt/sbin/in.tftpd
           server_args      = -s /mnt/tftpboot
           cps              = 100 2
           log_on_success   = HOST PID
           log_on_failure   = HOST
           disable          = no
    }
    
  3. Put the Ubuntu files in the folder /mnt/tftpboot (in my case). I copied the files of the last version of Ubuntu “Quantal”: http://ports.ubuntu.com/ubuntu-ports/dists/quantal/main/installer-powerpc/current/images/powerpc/netboot/
  4. Reboot the Mac Mini and enter the Open Firmware by holding “Option”+”Command”+”o”+”f”
  5. Type the following command to start the install:
    boot enet:192.168.2.100,yaboot
    

    With 192.168.2.100 the IP address of the machine where tftp is installed.

  6. Follow the Ubuntu installation steps and enjoy! :)

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Redirect traffic to a specific network

This is a little trick which can be useful in some very specific case.

For example, you could have a machine with two network cards. One of the network is behind a proxy and the other one is connected directly to the internet.
You might want to forward all the traffic for google.com to the network which doesn’t have a proxy.

To do this, I am using the command route:

route add <hostname> <target network>

For example:

route add google.com 192.168.101.1

Note that this command is available on both Linux and Mac.

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Install s3fs on Amazon Clouds

s3fs is a FUSE filesystem that allows you to mount an Amazon S3 bucket as a local filesystem. It stores files natively and transparently in S3 (i.e., you can use other programs to access the same files).

The following instructions detail the steps to install the program s3fs on an Amazon EC2 running Debian 5.0.5.

  1. Install libfuse
    First, you need to install the package libfuse manually as the one provided via apt-get is too old (s3fs needs a version greater than or equal to 2.8.4).

    wget http://downloads.sourceforge.net/project/fuse/fuse-2.X/2.8.7/fuse-2.8.7.tar.gz
    tar xzf fuse-2.8.7.tar.gz
    cd fuse-2.8.7
    ./configure --prefix=/usr
    make install
    
  2. Install libxml
    You can simply install the package provided by apt-get:

    apt-get install libxml2-dev
    
  3. Upgrade mount
    Because of a problem between fuse and mount, you need to upgrade the version of mount:

    wget http://www.kernel.org/pub/linux/utils/util-linux/v2.21/util-linux-2.21-rc1.tar.gz
    tar xzf util-linux-2.21-rc1.tar.gz
    ./configure --prefix=/usr --without-ncurses
    make install
    

    For more information about this issue, please go to the following page: http://code.google.com/p/s3fs/issues/detail?id=228

  4. Install s3fs
    You can now install s3fs using the following commands:

    wget http://s3fs.googlecode.com/files/s3fs-1.61.tar.gz
    tar xvzf s3fs-1.61.tar.gz
    cd s3fs-1.61/
    ./configure --prefix=/usr
    make install
    


Note that I wanted to use s3fs to create incremental snapshot-style backups with rsync. Unfortunately, as mentioned on the following page, it didn’t work because s3fs doesn’t support hard links: http://code.google.com/p/s3fs/issues/detail?id=46

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