Author Archives: Sunny Walia

RewriteRule: How to avoid passing query string when you redirect.

Today I ran into an issue which I could not figure out for quite a while. I was trying to redirect a url to another url using RewriteRule. It was supposed to be a pretty straightforward redirect which made it even more annoying than complicated ones. Hopefully somebody is able to explain what I am missing here and if my solution is a good solution or not.

I needed to redirect a url:  http://www.example.com/testpage.php?foo=bar to http://www.example.com/

So I added this to .htaccess file:

RewriteRule ^testpage\.php / [R=301,L]

This did do a 301 redirect as I wanted but query string passed so my redirected url looked like:  http://www.example.com/?foo=bar

Obviously this is not what I wanted so in order for me to fix it, I had to take a rather lame approach.  My new redirect is:

RewriteRule ^testpage\.php /? [R=301,L]

The only difference is the “?” after / for target url.  I am just curious to know why query-string was passed.  I have not used rewrites for long time but I do not remember this behavior.

SVN: How do you use svn command line on Windows with ssh tunneling?

If you ever used svn command line, you know it is not optimal to type in your password every time you do checkout, checkin, info, etc.  In linux world, it is very easy to setup keys to get around this.  Of course in the world of Windows it is not as easy.  Here are the steps you need to follow to get private/public keys working with your SVN under Windows using ssh tunneling.

Assumptions:  you will be connecting as user “root” to svn server located at “10.0.0.1”.  All your files will be saved at c:\ including your svn command line utility

First we will have to generate a key.  We can accomplish this by using a free utility called puttygen.  Run puttygen and click on “Generate” button.  You will have a key similar to below example:

Example of a key generated by puttygen

Example of a key generated by puttygen

Copy this, you will need it in few mins.  At this point, go ahead and create a private key by clicking on:  “Save private key”.  Save this as private.ppk on your C:\. 

Now let us log in to the svn server and add this public key to the authorized_keys2 (see setting up keys for step by step instructions).  I will assume you are using “root” as login.

vi /root/.ssh/authorized_keys2

Make sure when you paste, it is not broken into different lines.  All of the key should be one line.

Ok now back to your Windows machine.  Now we need to set up ssh tunnel to our server.  There are few ways of doing this but for our purpose, we will use another free program provided by the same developers as puttygen: download plink to C:\.  If you do not do this step, you will get following error:

svn: Can't create tunnel: The system cannot find the file specified.

Ok let us set the variables for svn.  Go to command prompt and type (you can also set this in your scripts and inside windows environment.  But since this post is to show you an example, we will just do this):

set SVN_SSH="/plink.exe" -i /private.ppk -l root

Now let’s run this one time manually to cache key:

/plink.exe -i /private.ppk -l root 10.0.0.1

Press “y” when it asks you to save.  Type exit and get back to your prompt.

Ok now we can test our svn utility.

/svn info svn+ssh://10.0.0.1/svn/testrepo/trunk/

This should display output similar to:

Path: trunk
URL: svn+ssh://10.0.0.1/svn/testrepo/trunk
Repository Root: svn+ssh://10.0.0.1/svn/testrepo
Repository UUID: b9143312-b1a1-11ba-a111-11cdcd1d2222
Revision: 10
Node Kind: directory
Last Changed Author: root
Last Changed Rev: 4
Last Changed Date: 2008-11-18 15:18:47 -0800 (Tue, 18 Nov 2008)

Now you are ready to script your checkouts, do checkin’s with out having to type in your password, etc.

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DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

sshfs: How do you install sshfs and fuse? [CentOS/Linux/Redhat]

One may wonder what is sshfs and why would you want it?  Well simply put, sshfs allows you to mount another server’s filesystem into a folder on your local system which in the background is doing ssh commands and transfers.  As a mounted folder, you are able to move about and copy files back and forth as everything was on local server.  As you can see this makes it very easy for you to work with files on multiple servers.

Note:  you only have to do the following installations on the server where you are doing the mounts on.

Let us download and install the filesystem framework which is a requirement for sshfs called fuse.

wget http://voxel.dl.sourceforge.net/sourceforge/fuse/fuse-2.7.4.tar.gz
tar zxpfv fuse-*.gz
cd fuse*
./configure

If you get the following error, you will either have to point to the location of the kernel source or install it if needed.

checking kernel source directory... Not found
configure: error:
*** Please specify the location of the kernel source with
*** the '--with-kernel=SRCDIR' option
configure: error: ./configure failed for kernel

In our case here, we will be installing the source using yum.

yum -y install kernel-devel

Once installed, you will have to find out the directory it is installed in

ls -l /usr/src/kernels/
total 4.0K
drwxr-xr-x 18 root root 4.0K Oct  7 14:50 2.6.18-92.1.13.el5-x86_64/

./configure --with-kernel=/usr/src/kernels/2.6.18-92.1.13.el5-x86_64
make && make install
cd ..

Now let us get sshfs source and install it.

wget http://voxel.dl.sourceforge.net/sourceforge/fuse/sshfs-fuse-2.1.tar.gz
tar zxpfv sshfs*
cd sshfs-fuse-*
./configure

If you get the following error:

checking for SSHFS... configure: error: The pkg-config script could not be found or is too old.  Make sure it
is in your PATH or set the PKG_CONFIG environment variable to the full
path to pkg-config.

OR

checking for SSHFS... configure: error: Package requirements (fuse >= 2.2 glib-2.0 gthread-2.0) were not met:

No package ‘glib-2.0’ found
No package ‘gthread-2.0’ found

You need to install glib2.  Do the following:

yum install glib2-devel

Once installation is done, continue with configure.

./configure
make && make install

After installation is done, we can move on with testing the installation:

cd /mnt
mkdir test
sshfs 10.0.0.2:/ test

If you get the following error,
sshfs: error while loading shared libraries: libfuse.so.2: cannot open shared object file: No such file or directory
execute this: NOTE: this is for x64 system. If you have 32 bit system, you have to symlink to /lib instead.
ln -s /usr/local/lib/libfuse.so.2 /lib64/
Let us try mounting again:
sshfs 10.0.0.2:/ test
At this point it would be like if you were making a ssh connection to 10.0.0.2 You will have to type in a password to get the mount to happen. You may get the following error: fuse: device not found, try 'modprobe fuse' first

If you do ‘modprobe fuse’, as they tell you to, and you get:
modprobe fuse
FATAL: Module fuse not found.

That means your running kernel is not the same version as the one you compiled with. You have two options here:
1) you can upgrade your kernel by typing: yum update kernel
2) find the source files for the kernel you have running and recompile fuse.

I went with option 1. Once you do the update, reboot and try doing modprobe fuse again.

At this point we can try doing the mount again.
cd /mnt
sshfs 10.0.0.2:/ test

If you do not get any errors, do df -h to see the mount:
...
sshfs#10.0.0.2:/ 1000G 0 1000G 0% /mnt/test
...

At this point you can browse 10.0.0.2 server filesystem as it was local on your server.

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DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.

Lance Armstrong come back to cycling to raise awareness of the global cancer burden

I know this is not one of my normal type of posts, but I really wanted to get this out to raise some awareness on the topic of cancer which most of us do not think about because it does not affect us directly.  It is sad how many people are affected by cancer and how many people die every year because of losing fight with cancer.

It is wonderful when famous people who can help make a difference do things to help a cause.  One of those people is Lance Armstrong, winner of Tour de France a record-breaking seven consecutive years.  He is also a cancer survivor.   Today I found out that Lance Armstrong announced that he is coming back to professional cycling in order to raise cancer awareness. Below is the full press release from livestrong.com website.  You can also visit the site to watch the video:

“I am happy to announce that after talking with my children, my family and my closest friends, I have decided to return to professional cycling in order to raise awareness of the global cancer burden. This year alone, nearly eight million people will die of cancer worldwide. Millions more will suffer in isolation, victims not only of the disease but of social stigma. After the passage of Proposition 15 in Texas, a $3 billion investment in the fight against cancer which is helping to make this disease part of the national dialogue in America, it’s now time to address cancer on a global level.”

Linux: How do you find out what your server’s outgoing ip is?

There are many times when I needed to find out my outgoing (or external) IP for the servers which are behind load balancers or firewalls.  I used to just login to another external server from the server in question and find out by looking at “who” what my external ip is.  Even though it works and I am so used to it, today I decided to figure out a more graceful way of finding my outgoing ip.  As most of us already know, whatismyip.com is the quickest way to find out your outgoing ip from the browser.  So I decided to use the same way on the servers.  So I issued a wget:

wget http://www.whatismyip.org

Well that does the trick.  But being lazy as I am, I did not want to have to cat the output file to find out the ip (plus there is no point of creating extra files and doing extra work to remove them).  So if you are ssh’ed in, you can issue following command (I am sure there is another way of doing it, but this is the quickest way I could think of):

wget -q -O - http://www.whatismyip.org

-O tells wget to redirect output to the following file (- being the standard out ).  So it basically echo’s output to our console.

-q makes wget run in  quiet mode so you do not see all of the connection/download/etc output.

That is it!  I am curious to know what other ways people use to get the same information.  Please share your way if possible.

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DISCLAIMER: Please be smart and use code found on internet carefully. Make backups often. And yeah.. last but not least.. I am not responsible for any damage caused by this posting. Use at your own risk.