Guillermo Garron

Introduction If you follow this blog, you may already know that I’m somehow obsessed with performance. But performance with low resources. I like to try to squeeze every drop of power from a server before upgrading it. Usually this is achievable tweaking configuration of the server. This time, I’ve been playing with Wordpress and a Small VPS server. Here the specs: 512 MB RAM Shared CPU Shared Disk Arch Linux 32 Bits It is the smallest Linode available by the time of this writing. I’ve tested Wordpress on different possible configurations: Apache, PHP, MySQL Standard Apache, PHP, MySQL and APC...

Installing needed software I’m using Arch Linux as the server, so let’s install needed software. First be sure you have the latest available software now install all the stuff. pacman -Syu Now install Nginx, PHP-FPM and MySQL pacman -S nginx php-fpm mysql Now let’s first take some steps to be sure mysql installation is secure. /etc/rc.d/mysqld start mysql_secure_installation In case you need help answering the questions, you can find some help in this page check the MySQL section. Configure PHP-FPM First let’s be sure PHP-FPM is using a socks instead of listening to a port, that makes it more efficient....

SCP Introduction scp stands for secure cp (copy), which means you can copy files across ssh connection. That connection will be securely encrypted, it is a very secure way to copy files between computers You can use scp to copy files from or to a remote server. You can also copy files from one remote server to another remote server, without passing traffic through your PC. You can use scp on Linux, Mac and Windows (using WinSCP). SCP Usage scp [[user@]from-host:]source-file [[user@]to-host:][destination-file] from-host Is the name or IP of the host where the source file is, this can be omitted...

To flush or purge the postfix mail queue, just enter this command postfix -f But if you need to delete an individual email from the queue, you’ll first need to see the queue. Traditionally you use mailq this time we’ll use: postqueue -p And the output should show all messages in queue: 5642B4D8647* 1683500 Tue Jun 3 08:37:27 xxxxxx@xxxxxxx.com rrrrrrrrr@hotmail.com 9359B4D82B1* 1635730 Tue Jun 3 08:36:53 xxxxxx@xxxxxxx.com yyyyyyyy@hotmail.com The first number is the message ID, if you only want to delete one of them, enter: postsuper -d 5642B4D8647 That will only delete one email for the queue, that specific email...

To have the correct time and date in Linux is very important, a lot of things depends on it. It does not matter if you are using Linux to power your personal computer or you have a Linux server. The server and system clock needs to be on time. Set date from the command line date +%Y%m%d -s "20120418" Set time from the command line date +%T -s "11:14:00" Set time and date from the command line date -s "19 APR 2012 11:14:00" Linux check date from command line date Will show you something like this: Thu Apr 19 15:17:34...

This is a small manual of iptables, I’ll show some basic commands, you may need to know to keep your computer secure. Basic commands List rules iptables -L This is going, list the default table “Filter”. Edit: You may prefer to use iptables -L -vn to get more information, and to see ports as numbers instead of its names. List rules in specific table iptables -L -t nat You can also list the other tables like: mangle, raw and security. You should consider reading a bit more about tables. You can do it in the Tables section in the man...

Introduction In the past, and for some years I’ve run my blog with the help of Drupal, in that time and in the first months, I’ve got Slashdoted, and Dugg three times, all three times my server went down. Since Then I’ve become obsessed with tweaking my server configuration to support the load of Slashdot, Digg and the like. I’m not running my blog over Drupal anymore, but I still like Drupal a lot, and this weekend I’ve been playing with Drupal 7 and Varnish, to see how it performs, under heavy load. I was trying to figure out a...

One of the best things computers do, is to execute repetitive jobs, and with *nix systems that is done using cronjob. I usually want my jobs to run every X amount of time, let’s say every 5 minutes, or every 12 hours. Here is how: Edit your cronjob file by running crontab -e command Add the following line for an every-5-minutes interval. /5 * * * /path/to/script-or-program Save the file, and that is it. If you want to do it every 12 hours, add this line when editing crontab file. 0 */12 * * * /path/to/script-or-program That will run on...

When for any reason, one of the margins of your window goes out of boundaries, specially when is the top margin, which is out of the boundaries of the screen. Move or resize to put it inside boundaries again is not a easy task, in those cases, what you can do, is resize using the keyboard. Just press ALT + F8 and the cursor will become a small cross, then you can move the mouse to the direction of the margin you want to resize. It will lock the margin and you can resize using the mouse. Hope this small...

When for any reason, one of the margins of your window goes out of boundaries, specially when is the top margin, which is out of the boundaries of the screen. Move or resize to put it inside boundaries again is not a easy task, in those cases, what you can do, is resize using the keyboard. Just press ALT + F8 and the cursor will become a small cross, then you can move the mouse to the direction of the margin you want to resize. It will lock the margin and you can resize using the mouse. Hope this small...

If you are planning to use Amazon S3 services, and you own a Mac, you may want to install s3cmd command from s3tools in your Mac. Here is how: First you need to get the software, you can download from here. Then just run: sudo python setup.py install And finally configure it running: s3cmd --configure. You can read more about how to use s3cmd

I’m now using Amazon S3 as my web server for this site. I’m uploading the files to it either from my Arch Linux Computer, or from my Macbok Pro. To do that, I’m using s3tools. It is a set of tools to be used from the command line either on Linux or Mac. To install it on the Arch Linux box was as easy as: pacman -S s3cmd Now, you have some sub-commands with s3cmd, but the first think you should do is to configure it, so run: s3cmd --configure You should not run the above command as root It...

Because of my implementation of static comments on this blog, and because of my need that all these comments should be sent to me via email. I needed an email server on my Linux, where I run Nginx. I decided to install postfix pacman -S postfix In my Arch Linux server. But to send emails from a “personal” computer now a days is not an easy task, and some of the emails may be rejected, because my, IP does not have a reverse DNS record, and some other issues. Because of that, I decided to make postfix relay on Gmail,...

Arch Linux is turning 10 this month. Ten years that have gone so fast, it is the same time since my first daughter birth. I can still remember like yesterday being in the Hospital seeing her fragile body and now she is my best friend. Something similar happens to me with Arch Linux, I’ve not knew it the very moment it arrived to this world, I’m working with it since 2008 so for only four years. I’ve started with RedHat Linux, then I moved to Fedora, then to Ubuntu and after that to Debian (I love Debian). But when I...

Introduction There are some situations, when you need to start an action or run a command when a given file has changed in your file system. The real life example I have is as follows: I have a git repository, from where I manage this blog, I have a remote branch of it on the same server, from where Nginx serves this pages. I also have another remote branch in my Macbook Pro (With the correspondent Time Machine backup). But, I’m a paranoid guy, so I just want more backups. I decided I wanted to backup all my blog files...

This is a very useful command, find and I have written about it before, today I want to share with you how to use it to find and copy files. What makes it wonderful, is that is can locate files all over your disk, and copy all those that match a specific criteria to a given folder. Pretty useful, if you want in example, send all log files to a given person. Continuing with the example above, lets find all .log files and copy them to a folder. First create that folder. mkdir /tmp/log-files Then find and copy all .log...

Let’s say you have two folders which are supposed to have the same information each one of them, but don’t really know. How can you check if they really have the same info? You can use diff First thing, create a scenario to check how diff works. I’ll create two folders with subfolders and files in them so you can see diff in action. /folder1/code /folder1/compiled /folder1/media /folder1/assets Now Folder2 structure /folder2/code /folder2/compiled /folder2/media /folder2/logs Finally I’ll add some files in some of the folders. In /folder1/code there will be a file named code.sh with this content cd /tmp/ mkdir...

One thing Ubuntu lovers like about Ubuntu is that it is “user friendly”, to me, it is “user friendly” only if the user doesn’t know what he is doing. As an example I have automatic updates, it may be convenient that your operating system search for updates for you (If you do not know how to do it, or do not want to do it by yourself). But it is also annoying to have a pop-up appearing when you are working, just to remember you something you already know. In my case, I’m using this Netbook mainly on 3G connection,...

I really like Arch Linux a lot, it is my favorite distribution, one thing I like a lot, is how easy is to install software from sources, and configure it to fit your needs. We will see two ways of doing that, the first one is when the software is available in the official Arch Linux repositories. The second is when the software is not in the official Arch Linux repositories. For the first one we will use ABS (Arch Build System) and for the second we will use AUR (Arch User Repository). Let’s start with the needed packages for...

I’m using Ubuntu Linux on my Acer Aspire One, actually I’m using Ubuntu on it, by default when you close the lid the laptop goes to “suspend mode”, instead I prefer it to go to “hibernate mode” because in suspend it still uses battery juice to keep the contents in RAM, but in hibernate mode it copies all RAM contents to the disk, and then turn off the computer. When you restart from hibernate, the OS reads the contents from the disk and put them in RAM again and you can continue your work from there. Yes, hibernate is slower...

If when trying to configure a network printer, using Gnome over Ubuntu 11.10 you get this error: FirewallD is not running. Network printer detection needs services mdns, ipp, ipp-client and samba client enabled on firewall. You will have to find a workaround, and one possible one is to open a window terminal and run: system-config-printer Hope this helps you when trying to configure your new printer with your Ubuntu laptop or desktop computer.

I have not been an Ubuntu user since 2009, but it is over a year since I want to test Ubuntu with Unity, this week I finally did, I’m not at home right now, and I used to travel with my Macbook Pro, but I have just acquired an Acer Aspire One. I tried to install Arch Linux on it from a usb key, but that left me with a computer with only a text based Linux. I like that about Arch Linux, but the Internet in this Hotel sucks, so I managed to download Ubuntu 11.10 and installed it...

You may have already know how to do this, but just in case, I’ll put here this small tip. If you want to backup using rsync, or just transfer some files from one server to another, being them Unix, Linux DSD or Apple’s OSX, you can do it using rsync. What I like about this tool, besides it keeps incremental backups, is that you can easily exclude some folders from the backup. Let’s say you have this folder structure. /home/user/documents /home/user/pictures /home/user/movies /home/user/backup Now suppose you want to copy them to your laptop, but you do not need the movies....

I have some movie DVDs, that I bought some time ago, I noticed that some of the started to degrade, specially because my boy plays with the DVD as if it were a toy. So, what I need was to create an ISO file from them and store them on my computer, then I can play them on my PC for them: In case you don’t remember how to create an ISO file from a DVD, here is how. sudo dd if=/dev/cdrom of=cd.iso Now that you have the DVD image on an ISO file, it is time to mount and...

A friend of mine called me today telling me he had to open a file that ended in PDF, but he was not able, I guided him to install Adobe reader on his Windows XP computer, but it was not easy as I was not watching the same screens he was, so I preferred to convert his PDF to JPG. He sent me the file via email, and with this simple line on my Arch Linux computer I converted the three pages PDF file into three JPG files. convert -density 300 file.pdf file.jpg You will have to install imagemagick first...

Today I’ll write about OpenVPN, and how to establish a VPN between two computers. The scenario There are two offices. The headquarters The branch office In this scenario the administrator wants all traffic of the branch office to be routed via the headquarters Internet router. This can be desirable for example if you have your branch office in a country where you suspect the Internet provider or the government may be sniffing your traffic, or just because you want to have full control of the pages and sites the workers at the branch office can access. In this scenario, we’ll...

This happens to me every time I want to install a new distribution of Linux in my Desktop PC, I just can’t remember what is the model of my video card so I can install the correct drivers. Fortunately Linux has enough tools to help you, and this time the tool is lspci. Let’s see how simple it is: lspci | grep VGA And you will get an output like this: 00:02.0 VGA compatible controller: Intel Corporation 82865G Integrated Graphics Controller (rev 02) That was simple and easy.

Today I’ve found that my CPU was throttling at 100%. The culprit was logrotate, or at least that was what I thought when I took a look at htop and saw that logrotate had been running at 100% for 10 hours straight. I then used du, in the /var/log/ folder to find which was the folder that was so big to have logrotate so busy, it happened to be nginx. After reading the configuration files, I found the problem. In the file /etc/logrotate.d/nginx that was the default installed by Nginx I could see this contents: # Copyright 1999-2011 Gentoo Foundation...

4 reasons to have Live Linux at home Linux became real part of our lives. You can meet anywhere... in your appliances, mobile phones, internet servers, desktops and laptops.In most cases this is either "embedded" or "installed" version of Linux. But there is another type of Linux operating systems which you should also consider. And I recommend you to have at least one at home... Why?Live Linux is operating system which can be booted directly from removable media: CD, DVD or USB stick. It does not require installation. In most cases it only uses RAM to store all the data,...

This is a small tip if you want to remove a line from a file, this is particularly useful when you get this message: Warning: the ECDSA host key for 'garron.me' differs from the key for the IP address '200.87.133.237' Offending key for IP in /home/gentoo/.ssh/known_hosts:20 Matching host key in /home/gentoo/.ssh/known_hosts:48 Are you sure you want to continue connecting (yes/no)? So in this case I may use this command: sed -i 20d ~/.ssh/known_hosts You can use it in other situations as well.

When you are compiling there are times, when you need to install a given library, but the problem is that you do not know which package to install. I mean you can’t install the library itself as it is contained in a given package, you first need to know which package it belongs to. Once you know that, you can install that package and continue with your job. Let’s now see how to do it in some Linux distributions. Let’s start with the most famous Linux distributions Debian, Ubuntu and derivatives We’ll use apt-file. First install it. apt-get install apt-file...

How fast things change in this world now a days, you can’t sleep a day without, being left behind. Just a few weeks ago I wrote about Chrome OS “I still do not see too much uses for it”, I was saying that mainly because, you needed to be “connected” in order to use it. Two days ago, Google announced that now, using Chrome, you can use Gmail, Calendar and Google Docs while off-line. As you can read in that post: When we announced Chromebooks at Google I/O 2011, we talked about bringing offline access to our web apps, and...

Today a post about 9 million hits per day with 120 MB RAM on Hacker News, called my attention. As the guy who wrote that post, I’ve trying to make my blog be ready for a rush of visits. As him, I’ve been hit in the past from Digg (Twice) and from Slashdot once, that was when I was beginning and I had Drupal (no optimization) running in a shared hosting server. The server took my page out, because I was making too many requests to the MySQL database. Sure I was, I had Drupal modules showing recent comments, showing...

Introduction From Wikipedia: A character encoding system consists of a code that pairs each character from a given repertoire with something else, such as a sequence of natural numbers, octets or electrical pulses, in order to facilitate the transmission of data (generally numbers and/or text) through telecommunication networks or storage of text in computers. Most modern web browsers feature automatic character encoding detection. Maybe the most used Character encoding are: UTF-8 ISO 8859-1 If you want that your web pages look the way it should, the documents (html files), should be created using the same encoding that the browser will...

You have decided it is time to start your blog, and you are not just any person. You are a Linux geek, so which is the best platform for your blog? Before answering that question let’s consider these other things: You want to be the owner of your content You want your server be able to handle the load if a post of you get listed in /., Reddit or Hacker News. Now, as we know, you are a Linux geek, you are not going to host your blog at posterous, tumblr or wordpress right? Of course not!. You are...

This is usually not needed, but if for some reason you need to increase the Swap memory of your system, I’ll show you now, how to do it. You can read more about virtual memory if you want. Now let’s see how to increase, or create a swap file, to be used for Linux as virtual memory. First we need to create a file. sudo dd if=/dev/zero of=/mnt/file.swap bs=1M count=512 We are instructing Linux to create a file of 512 blocks of 1Meg each. You may need to change that value according to your needs. sudo mkswap /mnt/file.swap This will...

Two months ago we celebreated the IPv6 day, and now that we know that IPv4 addresses are exhausted, we need to start using IPv6, some datacenters like linode are already offering IPv6 native support. If you are running your website over Nginx, enable IPv6 support is quite easy. Just open nginx.conf file with your favorite text editor and look for this line: listen 80; Or something like that, and replace it with: listen [::]:80; You are done, just restart Nginx and you have support for IPv6, provided that you already have an IPv6 address assigned to your server.

If you check your website stats, you will see that most of your visitors are using modern web browsers, those browsers now support gzip (compressed) content. What does that mean?. Of course you know about zipping a file or group of files to make them use less space, maybe you zipped files to send them via email. Well, today web servers can also compress the content before sending it to your readers, speeding up your site, and lowering the bandwidth requirements of your server. When a visitor’s browser ask for a page of your site, it will let your server...

If you get this error General error: 1030 Got error 134 from storage engine when trying to access any PHP application that uses MySQL, do not panic as the problem is really easy to solve. All you have to do is repair your tables, you can use PHPMyAdmin for that: Login into PHPMyAdmin Choose the database you want to work with. Check the boxes of all your tables. Below the tables, there is a drop down menu, choose “repair table” from it. You can also use the MySQL command line, mysql>use [database]; mysql>check table [your_table]; If you see any other...

There are a lot of options to share files with your co-workers, if you are using Linux, you can use Python, you can start an FTP server, use ssh, or “the cloud” (Google Docs, Dropbox and others). But an old piece of software is still very useful today, that software is Giver. You can easily install it on almost any Linux computer in your home/office network, and after that start sharing files is as simple as a click here and a click there. Once you have it installed, you will see something like this window. You will be able to...

Reviews of Linux distributions: I’ve read a lot of them, and I’ve write some too, I’ve been thinking about how a good review should be, what it should include, and what it should aim to. In the comments section of my friend’s blog, started a nice discussion. In the review the writer stated that he has only installed the distribution under test in a virtual machine. One commenter said: ”… To write a good review, you need to really install the distribution in you computer, and use it for some fair amount of time, not just install it in a...

Introduction I started blogging about Linux, in 2007, it all started because I was writing almost daily in some Linux distribution lists, so I thought it could have made sense to put all my writings on line in a single place, so others can use them. I started writing about my discoveries, how to tutorials, and other things, mainly as notes to myself and from time to time pointing other people from the forums to my posts, when they were looking for a solution I have already wrote about. I started using Joomla, it was OK for some months, the...

Part of the Best Practices for Speeding Up Your Web Site is Use Cookie-free Domains for Components. And what does this means? It means that you should serve your static content, from a domain where no cookies have been sent to the browser. How can you achieve this? You best bet is to create a new domain, it can be a sub-domain, something like: static.yourdomain.com or a complete new domain, like static-yourdomain.com, and there you can create a subdomain to use, let’s say images.static-yourdomain.com Now you can use Nginx to serve your static content from this new domain. We’ll first...

This is another small tip, but very useful for webmasters, you know that a webpage loads faster if you define the height and width of an image in the html code. But what if you do not know that info of a given image?, you can always fire the GIMP or any other graphical application to check the size of a given picture but you can easily do it from the command line. identify picture.jpg The output of the that command may be something like this: picture.jpg JPEG 1500x1000 1500x1000+0+0 8-bit DirectClass 104KB 0.000u 0:00.000 You now know that this...

I’ve not completely decided this, but I’m seriously thinking about moving Go2linux blog to Garron.me I’m not going to remove Go2Linux nor move all posts to a new location, I will just stop posting there and continue to post in the new site. The main reason is, that I want to post about not only Linux but about other topics and that is not possible under go2linux domain, at least it does not make sense to me, also I do not want to be keeping two sites as that consumes time, and I prefer to use that time in writing...

For good SEO you better have only one url for every post or article in your site, as having two uris responding with the same content may lead to duplicate content and that is penalized by the search engines, specially by Google which is the biggest by far. So, if you are using Nginx and want to remove the trailing slash from all URIs in your site, so if someone types: http://yoursite.com/ will be automatically redirected to http://yoursite.com Here is the code you need to add to your nginx.conf file. rewrite ^/(.*)/$ /$1 permanent; That goes in the server section...

Add a line in a specific position with Linux If you need to add a line to a file in Linux, and you need to add that line in a specific position of the file there is an easy solution, even if you need to do it to hundreds of thousands of files. Consider this file: line 1 line 2 line 4 As you can see we missed line 3, so to add it just execute this command: sed '3iline 3' filename.txt Parts of the command sed: is the command itself 3: is the line where you want the new...

IntroductionUnless you have been living under a rock this last two years, you surely know what Google Chrome OS is. Just in case you don’t: Google Chrome OS is a Linux-based operating system designed by Google to work exclusively with web applications. Google announced the operating system on July 7, 2009, and made it an open source project, called Chromium OS, that November. So what we have here is yet another operating system, but this one is different from the others, as it is designed to work only when connected to the cloud, besides a media player and a browser...

My brother bought a Nokia N900 some months ago, and I loved the Linux support, being a Linux fan, I just love how you can get into the terminal window with no need to add apps, or anything.Now I'm exited to read that Nokia will release a MeeGo phone, the N9 one.MeeGo from Wikipedia: MeeGo is a Linux-based open source mobile operating system project. Primarily targeted at mobile devices and information appliances in the consumer electronics market, MeeGo is designed to act as an operating system for hardware platforms such as netbooks, entry-level desktops, nettops, tablet computers, mobile computing and...