How to colorizing cat command output or files using ccat app on Linux or Unix system

Posted on in Categories Command Line Hacks, Howto last updated August 30, 2017

The [nixcmd name="cat"] (short for concatenate) is one of the most frequently used flexible commands on Linux, Apple MacOS X, *BSD (FreeBSD / OpenBSD / NetBSD), Unix-like operating systems. It is useful to display text files on screen, copy text files, combine text files, create new text files and more. If you cat command with colours, try ccat app.

I put a cronjob in /etc/cron.{hourly,daily,weekly,monthly} and it does not run and how can I troubleshoot it?

Posted on in Categories Cloud Computing, Howto, Open Source, Web Developer last updated August 27, 2017


Recently I created a simple shell script called backup.sh in /root/scripts directory to just backup MySQL database and dumped it to /nfs/mysql/ directory. I put a file (more like used the ln command to create a soft link ) in /etc/cron.hourly/ and it doesn’t run. There was no error in systemd log or cron log. Why is my cron job was not working, and here is how I troubleshoot it.

Linux/Unix desktop fun: Bastet Tetris(r) clone with block-choosing AI for console

Posted on in Categories Linux Games, Open Source last updated August 18, 2017

Xkcd - hell
Do you love the puzzle and Linux/Unix-like system? Command line? Try ncurses based Tetris clone which is harder than every other Tetris out there. From the project home page:

Have you ever thought Tetris(R) was evil because it wouldn’t send you that straight “I” brick you needed in order to clear four rows at the same time? Well Tetris(R) probably isn’t evil, but Bastet certainly is. >:-) Bastet stands for “bastard tetris”, and is a simple ncurses-based Tetris(R) clone for Linux. Unlike normal Tetris(R), however, Bastet does not choose your next brick at random. Instead, Bastet uses a special algorithm designed to choose the worst brick possible. As you can imagine, playing Bastet can be a very frustrating experience!

5 Awesome Open Source Groupware Software Suite

Posted on in Categories Open Source last updated August 3, 2017

Groupware (also known as “Collaborative software”) is nothing but an app that helps users in everyday tasks such as calendar/scheduling, address books, email, forums, mailing lists, IM, wiki and more. The use of collaborative software in the work space creates a collaborative working environment. You can synchronize and share your files and photos easily using your hardware while maintaining privacy and security. Here is a list of 5 of them that you must know.

How to fix IPMI KVM JAVA BMCMD5withRSA and is treated as unsigned error

Posted on in Categories Datacenter, Hardware last updated July 8, 2017

Like any good sysadmin, I kept my servers and desktop side up to date and patched all the time. However, recent Java updates have broken my IPMI KVM Java Applets on Dell, IBM, HP, Supermicro and FreeNAS mini servers. You will get an error that read as follows:

Unsigned application requesting unrestricted access to system. The following resource is signed with a weak signature algorithm MD5withRSA and is treated as unsigned.

Why port 80 (HTTP) reported as open by nmap when it is closed?

Posted on in Categories Security last updated July 2, 2017

Why are some ports reported as open by nmap?
I recently setup a small server which is running Debian 9. The purpose of this machine is to run OpenVPN server on port 443 to bypass censorship. It runs the following services and nothing else:

  1. Squid on private IP belongs to VPN pool (10.8.0.1:3128)
  2. SSH on private IP belongs to VPN pool (10.8.0.1:22)
  3. DNS resolver on private IP belongs to VPN pool (10.8.0.1:53)
  4. OpneVPN on public IP port 443 (server_public_ip_address:443)