Building R on RedHat Linux 6

Newer versions of R(>=3.3.x) will not build without newer bzip2, zlib, libcurl & pcre. These dependencies are not available on older version of RHEL & CentOS i.e. anything below RHEL & CentOS 7. This blog post is a step-by-step journal of what I encountered when trying to compile & install R v3.3.2 on a CentOS 6 host.

Temporarily Clearing Bash Environment Variables

At times I’d just like to run a script or a program without using my current or pre-existing shell environment variables. Running bash -l doesn’t really help because it just starts a new bash shell login with the same environment variables from your ~/.bashrc or profile.d system-wide settings. Well, the other day I discovered prefixing your program/script with env temporarily clears your environment variables so that your script just runs with totally no variables!

GPG Subkeys

OpenPGP supports subkeys which are like the normal keys, except they’re bound to a master key pair. A subkey can be used for signing or for encryption. The really useful part of subkeys is that they can be revoked independently of the master keys, and also stored separately from them.

Enabling MySQL Binary Logs

MySQL binary log contains records of all changes to a databases—both data & structure—as well as how long each statement took to execute. It logs SQL statements such as CREATE, ALTER, INSERT, UPDATE & DELETE with the exception of SELECT & SHOW which have no effect on the data.

Recovering ZFS Pool

Once in a while, more so after doing major system upgrades, you might end up losing your ZFS pool due to unknown circumstances. In this post I’ll talk about how you can easily recover your pool. Your / partition should NOT be on ZFS pool.

Mounting Partitions Using Systemd

Recently, I discovered you can mount partitions using systemd.mount by writing a mount unit file. In this blog post, we”ll talk about systemd.mount & how you can use it to mount partitions.

Yum/DNF Keep Old Packages

When you upgrade packages on RedHat based systems, the newer package replaces the older one except for install only packages e.g. kernel packages. Upgrading kernel package(s) with yum, dnf and even apt leaves 3 older versions—by default—of the kernel package(s) on the system. This can be useful in cases where you need to use to an older version.

Rebooting server(s) using Ansible

Ansible provides useful tools which we can use to for various purposes. In this blog post, we’ll talk about rebooting servers using ansible & pausing the playbook by waiting for a given amount of time for a given service on a given port to start.

Validity of SSL Certificates

OpenSSL provides several options for implementing SSL & TLS network protocols that you can use to securely communicate with a server. In this blog post, we’ll turn our attention to SSL certificates & the priceless information they contain.

Hello blogging world :)

so after several months—if not years—of procrastinating whether I should or should not blog, I’ve finally decided to leave my comfort zone and face my greatest fear—blogging!!