How to Remove All Commented Lines or Lines with a Specific Pattern in vim?
Recently I was doing lot of text editing on one of my server (for maintenance activity) – where I need...
Linux
How to Upgrade Sendmail to the latest version on CentOS
Recently I had to upgrade Sendmail version 8.13 to the latest version 8.15 on CentOS 5. If you are someone planning...Troubleshooting Request Tracker version 3 Error – Attempt to free unreferenced scalar, Perl interpreter
I have been using Request Tracker version 3 for quite sometime and it worked great. But suddenly the RT server...Download OpenStack Command Line Interface Cheat Sheet! – Most Commonly used Commands
OpenStack is a great platform to setup your own cloud environment. But for novice, it’s not that easy. Yes, there...RT:Request Tracker – Error : rt-mailgate – Undefined server error – 500 Can’t connect or verify Certificate [Solved]
I have installed Request Tracker (RT) in my office and it was working well until today. Suddenly, it stopped accepting ticket requests via Mail and there was...How to Create, Extract or Open RAR file in Linux?
Everyone might have used RAR files in Windows, but using it on Linux is not straightforward. None of the Linux operating...Error: xenstore-read: xs_open: No such file or directory on DomU [Solved]
Question: Hi, I have installed Xen Hypervisor version 3.1 on RHEL machine, which runs two CentOS VMs on Dom0. I would...Error : Xend Start – /proc/xen/capabilities: No such file or directory [Solved]
Question: I was able to install Xen Hypervisor successfully on Red Hat Enterprise Linux release 5.5 and booted the system...Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again [Solved]
Question: I was trying to install Xen server on CentOS 6.4 via yum install xen, but yum failed with an error...How to use Wget to recursively download files from a web directory?
Question: My company’s intranet website hosts GB’s of software tools and applications. I have been trying to download all of...How to Install Xen Virtualization Software on Linux and Launch a VM using virt-manager?
Question: I have a Red Hat Enterprise Linux version 5.5 operating system running on an Intel Xeon machine that supports...Error: Setup Command not found in CentOS VPS [Solved]
Hi, I was using setup command in one of my RHEL machine to configure firewall, network and system services. Recently, I...How to Login to OpenStack Instance or VM via PuTTY using Key?
Question: I installed OpenStack Icehouse on my test bed and was able to create instances successfully. But I was not...CentOS – semanage command not found error – The fix is here!
Question: I was trying to setup Apache web server on a different port other than port 80. For instance, on...Download free “IPv6 Cheat Sheet” for Network Administrators
As you all know, IPv6 is the next generation Internet Protocol that intended to replace IPv4, which still powers 97%...[Linux]: SSH Cannot switch to specific user with an Error “su: cannot set user id: Resource temporarily unavailable”
One of my colleague came with a problem that he was not able to login to a particular user account on a...Fix OpenSSL Vulnerabilities on CentOS, Debian, Ubuntu and RHEL! [1.0.1e-fips]
If you find your production machines using OpenSSL version 1.0.1, 1.0.0 and 0.9.8, then here’s a serious vulnerability reported on...How to solve erratic disk usage statistics from du (Linux command)
Recently on my Linux server box, one of the disk partition was full and had to delete 100’s of MB of...A Simple Guide to Install OpenStack Icehouse on CentOS – Two node Architecture
The word “OpenStack” is quite popular these days. You might have heard this word, even if you are not working in...OpenStack Icehouse Installation Errors and Solutions – CentOS
I have been trying to install OpenStack Icehouse on CentOS for almost a week (Since I’m doing this for the...