Julius Beckmann » Linux

Ubuntu: Create own or fix broken samba shared directorys

Julius — Mon, 30 May 2011 10:28:39 +0000

I recently wanted to create a shared folder with the attribute hidden, but did not want to change the /etc/samba/smb.cnf.

So i searched where the shares created by the gnome folder-properties window where saved. The directory is:

/var/lib/samba/usershares/

This is also the place, where you might fix a broken share by deleting the config file.

Kubuntu: Connect to hidden WLAN

Julius — Mon, 30 May 2011 10:10:26 +0000

Somehow the Network-Manager in Kubuntu can not connect to hidden wireless lan. But i found a simple workaround in the kubuntuforums.net:

Go in the Kubuntu Network-Manager and add a new connection with all the details of the hidden WLAN.

Now open a terminal and run this command:

sudo iwlist wlan0 scan essid NameOfHiddenWLAN

This will scan on the wlan0 device for a network with the name "NameOfHiddenWLAN".
A few seconds later, your Network-Manager might already have connected to the hidden WLAN, if everything was correct.

Linux: Count lines of code

Julius — Thu, 19 May 2011 09:41:15 +0000

I found a cool programm, that can count lines of code for several programming languages.
You can find it here: http://cloc.sourceforge.net/

Install

On a debian based box, installing is very easy:

sudo apt-get install cloc

Howto

Usage:

cloc --help

File/s:

cloc *java

Directory:

cloc src/

Example

I counted some of my Java lines:

src$ cloc *.java
      13 text files.
      13 unique files.
       0 files ignored.

http://cloc.sourceforge.net v 1.53  T=0.5 s (26.0 files/s, 2706.0 lines/s)
-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
Java                            13            189            140           1024
-------------------------------------------------------------------------------
SUM:                            13            189            140           1024
-------------------------------------------------------------------------------

Ubuntu: Backup/Copy network settings in Ubuntu

Julius — Mon, 02 May 2011 20:17:13 +0000

I did a clean install of Ubuntu 11.04 and copied all the needed configs from my old 10.10 installation. But i could not find the needed folders for the network and wireless settings, so i searched for them and this is what i found.

To backup or copy the network settings under ubuntu, you need 2 parts of your old system:

1. The .gconf part
You need to copy the folder where the network settings are stored, this is here:

/home/YOUR_USERNAME/.gconf/system

You can copy the whole folder and move it to the new system.

2. The Keyring
If you search for keywords or passphrases, you will not find any in .gconf/system.
The password for WLAN access are stored inside your keyring, which is stored here:

/home/YOUR_USERNAME/.gnome2/keyrings

You need this folder, if the gconf settings need a passphrase from your keyring.

Linux: Slow dd because of default blocksize

Julius — Sun, 01 May 2011 19:53:26 +0000

Today is backed up my SSD so i can install Ubuntu 11.04 fearlessly.
Problem was that dd was very slow, but i found a solution.

By default dd seems to use 512 Byte as default blocksize. This means copying 10 GB lets dd move 20 million blocks. This is very stressful for the computer.
You can speed the whole thin up by giving a bigger blocksize via parameter.

Example:

# dd if=/dev/sda2 of=/media/BACKUPHDD/Backup/SSD/system.img bs=4M

The optimal blocksize might depend from your hardware. If time is important, you might do some short tests with different blocksizes.

Ubuntu: Install on a Disk with less than 4.4 GB (Workaround)

Julius — Sun, 01 May 2011 15:37:24 +0000

I tried to install Ubuntu 11.04 on a 4 GB USB-Stick today, but was failed by the installer who wants at least 4.4 GB free space. This is unnecessary much, because a normal Ubuntu install will stay below 2.5 GB.
I found a "fix" that works like this:

1. Start Ubuntu from CD/DVD as a Live-CD (The "Test", not the "Install" Button).

2. Open up a console / terminal and enter the following code:

gksu gedit /usr/lib/ubiquity/plugins/ubi-prepare.py

This will open a python file that includes the "min_size" method.
Search for the line (around line 310) that says:

"min_disk_size = size * 2"

Change the code to this:

"min_disk_size = size * 1.4"

Then save and close the editor.

3. Start the installer on the desktop. It should ask now for about 3 GB.

Original fix posted by Nathan.

Linux: Change timezone on Debian/Ubuntu

Julius — Wed, 27 Apr 2011 13:35:24 +0000

Change timezone on your Ubuntu/Debian system by opening a Terminal and run this command:

sudo dpkg-reconfigure tzdata

Bash: Simple HDD/SSD speed test using dd

Julius — Tue, 19 Apr 2011 22:13:20 +0000

I wrote a (very) short script to test hdd or ssd speed using dd. You can find the code here:

hdd-speed-test-1gb.sh
and as text:
hdd-speed-test-1gb.sh.txt

The script uses dd and /dev/zero for writing a 1GB sized tempfile. Then the tempfile is written by dd to /dev/null. dd produces some output where the transfer speed is mentioned. Afterwards the tempfile is removed.
It is really just a tiny script, so i do not have to remember the dd syntax every few months.

Bash: Remove all .svn folders - Un-checkout from svn

Julius — Sat, 09 Apr 2011 12:14:33 +0000

If you want to send somebody parts of your svn repository, then you mostly do not want to give them your .svn folders with all the settings and base files inside.

I wrote a short command to remove all the .svn folders recursive from the current directory:

for dir in $(find . -name ".svn" -type d); do rm -rf "$dir"; done

find . -name ".svn" -type d
- Will list recursive all directorys named '.svn' in current directory.

for dir in $(...); do rm -rf "$dir"; done
- Will delete all items from the result of $().

If you do not want to type and remember that much, you can easily add this as a bash alias.
Open your .bashrc and add this line:

alias unsvn='for dir in $(find . -name ".svn" -type d); do rm -rf "$dir"; done'

The next time you start a bash, you have a new command "unsvn".

Bash: Rename all files inside current directory

Julius — Sun, 03 Apr 2011 14:04:18 +0000

Renaming all files inside a directory can be done with the following code.

find * -type f | while read FILE; do mv "$FILE" old_"$FILE"; done;

The code will take all filenames in the current directory, and append "old_" to the name.

find * -type f
- Will make a list of all files in the current directory.
while read FILE; do ...; done
- Will read from a list each line into the variable FILE.
mv "$FILE" old_"$FILE";
- Will rename the filename in the variable $FILE to old_$FILE. Check out the double quotes - they are important, otherwise filenames with spaces will break the move command.