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 …

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 …

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).  …

My friend today asked me how to convert all spaces in filenames under a specified directory to underscores. Also, at the same time lowercase all of the filenames. Here is a quick script to do what is needed. Let us start with creating some test data in a temp directory:

mkdir temp
cd temp
touch Foo FooO "Foo Bar" "FOO BAaR"
\ls | while read -r FILENAME
do
mv -v "$FILENAME" `echo $FILENAME| tr ' ' '_'| tr '[A-Z]' '[a-z]'`
done

Note:  I intentionally have slash in front of ls (\ls).  \ls means that we want to make sure there is no ls alias overwriting our command. This is needed if your system has alias setup to display ls in a different way instead of default listing.  mv -v shows us the filenames being renamed as your script goes through the whole dir.  Your output should be like:

`Foo' -> `foo'
`FOO BAaR' -> …

Server monitoring is a big part of running a solid web site.  As an admin, you must know what is going on your server.  One of the tools most Linux/Unix admins are used to is called “top”.  “top” by itself is a very powerful tool.  Here is a quick guide on how to read output from top:  introduction to load averages under top.  It just makes sense that somebody went and created httptop to monitor http traffic.

Install perl modules:

install Term::ReadKey
install File::Tail
install Time::HiRes

Now copy paste the script below and save it in a location and set +x attribute on it so you can execute it.  On my …

Most of the users who work with distributions such as: centos, fedora, redhat, etc use yum as a package update/installer. Most of them know how to do “yum update [packagename]” (to update all or [certain packages]) or they do “yum install packagename” to install certain package(s). But yum can do so much more. Here are some options you may find useful:

Following command will search for the string you specified. Generally this will give you all of the packages which has specified string in title or description. Most of the time you will have to look through a lot of output to find what you are looking for.

yum search string

Probably one of the most important options for yum is provides/whatprovides. If you know what command you need, you can find out what package you have to install in order to have that command available to you.

yum provides (or whatprovides) command

As a consultant, I do a lot of content migrations for clients. One issue I run into quite often is the encoding of databases, tables, columns differs between source and destination. Most clients do not want me to go and change the way their encoding is to fix issues since they are too afraid about messing with production data. Of course amongst other issues, it creates weird characters for data which is copied/pasted from Microsoft Word. You see weird characters like: ’ … – “ †‘

So if you just want to replace these with appropriate symbols, you may do it with a simple sql query. Note that below queries are without where clause. You may what to test it with one of your rows before making changes to the whole table. Of course, you should always backup your data before you try this out. If you have a dev system, that is even better. I put …

This weekend our networking guys decided to change ips for all of our servers. They also changed our subversion server’s ip. This caused some issues in the subversion world with developers who had checkouts pointing to ips instead of hostname, using command similar to:

svn co svn+ssh://192.168.1.10/svn/myrepos/ /home/mycheckout/

Now when they do “svn update” inside the their /home/mycheckout/ directory, they get an error:

We needed to point the checkout to the new ip. Easiest way to do this is to delete your checkout and re-checkout. Unfortunately, some of the developers had a lot of modified files which wasn’t checked in yet. I fixed it by issuing:

find /home/mycheckout -name "entries"|xargs /usr/bin/perl -w -i -p -e "s/192.168.1.10/10.1.1.10/g"

Find command helps us in finding all the files with name “entries” and xargs takes the filename and passes it to …

One of the things people tend to forget is the ability for web servers to compress content before sending it back to client. Client’s browser then uncompresses the data and displays it to the user. Pretty much all of the recent browsers support gzip compression. In this post, I will go over how to setup apache2 to use compression. First let’s see if your Apache installation has “deflate” enabled. You can check to see if you have deflate by typing:

# /usr/local/apache2/bin/apachectl -t -D DUMP_MODULES
Loaded Modules:
...
deflate_module (static)
...
Syntax OK

If you don’t have have deflate_module, you would have to recompile your apache with “–enable-deflate” option.

Going forward, I am going to assume you have deflate_module. Add the following to your apache conf file:

<Location />
SetOutputFilter DEFLATE
BrowserMatch …

Innotop is a very useful tool to monitor innodb information in real time. This tool is written by Baron Schwartz who is also an author of “High Performance MySQL, Second edition” book. [Side note: I highly recommend getting this book when it comes out (in June, 08?). Other authors include: Peter Zaitsev, Jeremy Zawodny, Arjen Lentz, Vadim Tkachenko and Derek J. Balling.] Quick summary of what innotop can monitor (from: http://innotop.sourceforge.net/): InnoDB transactions and internals, queries and processes, deadlocks, foreign key errors, replication status, system variables and status and much more.

Following are the instructions on how to install innotop on CentOS x64/Fedora/RHEL (Redhat enterprise). Most probably same instructions can be used on all flavors of Linux. If not, leave me a comment and I will research a solution for you. Let us start with downloading innotop. I used version 1.6.0 which is the latest at the time of …