You can easily see how hard (or not) a Redhat or CentOS system was running on any given day within the past month. For example, if you want to know how hard a system was working three days ago, you can. Here’s how. The “sar” command shows “todays” performance. It

This is how to resolve the CORS issue on an Apache server. The short of it is that a web page may require the browser to make Jquery calls to another server which rightfully rings alarm bells. Add the following to the Apache vhost on the target server – where

This article demonstrates how to install VirtualBox on CentOS 7 and RHEL systems. cd /etc/yum.repos.d/ wget http://download.virtualbox.org/virtualbox/rpm/rhel/virtualbox.repo rpm -Uvh http://epel.mirror.net.in/epel/7/x86_64/e/epel-release-7-8.noarch.rpm Install required packages: yum install gcc make patch dkms qt libgomp yum install kernel-headers kernel-devel fontforge binutils glibc-headers glibc-devel Check where the kernel headers went. We need that for a

This article demonstrates how to install Vagrant on CentOS 7 and RHEL. Note that as of recently, Vagrant is installed differently. Download it for your OS here “https://www.vagrantup.com/downloads.html”. The following is only if you want to do it the old way. sudo yum install ruby sudo gem install vagrant Find

This article explains how to set the inode limit on a tmpfs on a CentOS or RHEL server. The default inode limit may be too small if you intend to store many small files on it. The following will set the tmpfs resource to 2GB with a default inode limit

This article is a walk-through of how to use Siege to load (or performance) test a website. In this example the target is the Magento application. The question is “how many visitors can the target site handle while keeping page maximum load times below 10 seconds”? There are add-on tools

This is a list of things i do every time i log into a Linux server. It’s habit now and something you might consider doing too. Essentially we want to know who’s on the server, what the server state is and how different it is to normal. Check who’s on

If you try to rsync a subset of many files from a single directory, you might get the error “Argument list too long”. Actually, you can get this error with many bash commands. This article explains how to work around it. rsync -avz /images/* cdn.example.com:/images/ -bash: /usr/bin/rsync: Argument list too

This article explains how Varnish, Apache and NginX fit together and/or differ. Varnish is an excellent cache and speeds up web-sites significantly. Terminate the HTTP connection at Varnish on port 80 and point Varnish internally to an NginX server listening for HTTP on port 81 (they can’t both be on

In this article we’re adding a Samba 3 server to a Workgroup and configuring the Samba server to serve a printer. This article includes CUPS but not Printer Drivers. I’ve made some comments at the end of this article which are worth your time to read if you need direction

If you’re a system administrator and you’ve been asked to create a WordPress Multisite, you’re in the right place. You simply need to add the following line to the “wp-cofig.php” file right above the “/* That’s all, stop editing! Happy blogging. */” line. define(‘MULTISITE’, true); define(‘SUBDOMAIN_INSTALL’, true); define(‘DOMAIN_CURRENT_SITE’, ‘blog.example.com’); define(‘PATH_CURRENT_SITE’,

This article shows how to set and change the speed and duplexing of an Ethernet device. You can see more examples at “http://www.cyberciti.biz/faq/linux-change-the-speed-and-duplex-settings-of-an-ethernet-card/”. View the current settings: mii-tool The output will be something similar to the following. Notice only physical network devices are listed. eth0: negotiated 1000baseT-FD flow-control, link ok

This article shows an example configuration for NginX with php-fpm on CentOS 7. This is not a HowTo but rather something for you to copy/paste to help you on your way. The website domain is “www.example.com” and we’re serving SSL as well. You can ignore that part if you like.

This article demonstrates how to upgrade php-fpm to 7.0. This information is based on “https://webtatic.com/packages/php70/”. Get the repositories ready: rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm Do the upgrade: yum install yum-plugin-replace yum replace php-common –replace-with=php70w-common Confirm your work: php -v Share This:

This article shows how to expand a filesystem on a CentOS 7 or Redhat Enterprise Linux 7 system by adding a second disk/filesystem. The disk in this example is “/dev/sda” and it has two filesystems on it “/dev/sda1” and “/dev/sda2”. There is plenty of unused disk space available no “/dev/sda”.

This article walks you through the process of building a very simple program in assembly language in 5 minutes. Tutorial programs usually go by the name “Hello World” because that’s all they print out to the screen. Plenty of this information came from: http://www.tutorialspoint.com/assembly_programming/assembly_environment_setup.htm. Install the tools. yum install nasm

This article explains step by step how to create (spin up) an EC2 instance within AWS using Ansible and a few extras. Unlike 100% of other articles out there, this one actually demonstrates how to do it. Pay attention to the date of this article because things DO change over

When logged into the Varnish server, you can see which requests are most common using the commands below. These will help determine popular content and also assist with troubleshooting during high-load times. The following command shows the requests from the Internet to Varnish: varnishtop -i TxURL The following command shows

This article explains how to get around the problem of remote access to a non-public RDS database within Amazon’s AWS. The problem is that RDS databases can be set to public or private when being created but are not easy to change later due to DNS issues. There are ways

Just lately I reinstalled my Gentoo server and when it came to putting Handbrake back on the system Portage began complaining that it was failing to emerge automake version 1.11.6. After checking the system I could see that I already had version 1.15 but that should not be causing the

This article demonstrates how to disable logging for the bind / named service. Why? Because you may not like DNS errors filling up your logs. Unlike most of our articles, this is not focused on CentOS or Redhat. Add the following to the end of you “/etc/named.conf”. This file sometimes

I’ve previously documented how to configure Rsyslog to store logs in MySQL which gives a good tutorial on setting up MySQL as the Rsyslog backend and also remote logging to that Rsyslog server. To extend on that, you can easily view and filter the logs using the php web-app below.

Just a quick reference for setting up your Gentoo server to get its time from an NTP server either local or on the Internet. Get NTP onto the machine emerge –ask -jv ntp Edit the NTP config vi /etc/ntp.conf Comment out the servers that you do not need and add

This playbook will add the script “myscript.sh” to the target machine(s) “/etc/cron.monthly” directory thereby having it run each month by cron. You can simply change the location to have it go into one of the other cron.x locations. I’ve used ansible version “ansible 1.9.4”. — – hosts: all sudo: yes

You’ve dumped a DB from MySQL and didn’t use the “–no-triggers” option. Now you’re trying to import your data into RDS MySQL which complains that: ERROR 1227 (42000) at line xxx: Access denied; you need (at least one of) the SUPER privilege(s) for this operation You can solve this by

Minor cause of frustration when you are installing Apache on a server that some one else has configured, is that if they have not setup the hosts file correctly apache will refuse to start. The error is in /var/log/apache2/error_log and looks like below: Name or service not known: mod_unique_id: unable

MySQL will use the “/etc/my.cf” file to learn where to put its error log file. However, if you don’t specify it, you don’t have access to the filesystem or you’re simply confused, try this. First log into MySQL and then run the following: mysql> show global variables like ‘log_error’; +—————+————————————–+

This is a quick HowTo for Tomcat7 on Redhat Enterprise Linux and CentOS 7. The shortest answer to how to install Tomcat7 is to download it, extract it and start it. It runs natively on port 8080 so adjust your firewall accordingly or change the port that Tomcat wants to

In this tutorial we’re going to create a ZFS filesystem on Disk1 and then extend it to Disk2. We’re not going to worry about redundancy because this is a tutorial but ZFS does support common RAID types. We’ll configure ZFS for RAID0 (no parity, no redundancy). In the real world,

This article demonstrates how to add directories to your log rotation plan. For example, you may have a directory where you put custom logs for your applications or perhaps you want to rotate Magento (shopping platform) logs. You can use this method. You have to decide your retention and rotation

This article discussed removal of the “var/log/system.log” Magento log file. You can find this file in your Magento installation path. A command such as the following would help: find /var/www -name “system.log” Tip: replace “/var/www” with the path to your Magento installation. Removing the “system.log” file has no effect from

I ran into this error in the test lab today and figured I would document the cause. When you create a QEMU/KVM virtual machine using the command line virt-install or the graphical virtual machine manager you get an error similar to the following Error starting domain: internal error: process exited