Welcome to The Linux Page

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This site is a collection of my own work with Linux. Certain things are easy, others take time to decipher and if I ever need to repeat the work (which usually happens!), then I need to remember everything by memory or... have a site with all the steps taken and to take again.

The following are my most recent posts:

Publishing failed. Error message: The response is not a valid JSON response

Beep Brake -- you get distracted, we don't!

I installed a new Wordpress website and I was getting this error when trying to save pages and also when trying to go to a page once I switched the permalink to "Post name".

This is not a very clear error. Plus all the admin functionality was working like a charm so it took me close to forever to fix this one. (like a good 6 hours!)

The fact is I've got three a domain name with three different TLDs:

When I create the configuration file for Apache, I used another one which I just created ...

A group

Once in a while I want to add my user to a group and then right away make use of that group.

Unfortunately, in general Unix kind of forces you to re-log in for the new group to be attached to your account.

However, a command has been added, a while back, to do just that on the fly. Not something you would want to use in a script, but at least, it works for me when doing a few things here and there.

In my case, I wanted to run QEMU, which I hadn't done in a while, and the system told me that it could not open the KVM, the error: kvm permission denied.

The problem was that I was not ...

BIND errors between masters and slaves

Twin Apples

Using BIND as a Master and a Slave simultaneously

I got BIND on two servers (the named service). Each server is at the same time a master and a slave depending on the domain name. For instance, I host http://www.alexishouses.com on my server and http://www.m2osw.com on my company's server.

Up to here, easy.

The slaves are expected to update themselves whenever the master emits a change in a zone.

Somehow, one of my domain names would not work at all on the slave (company's server). I searched and searched and I just couldn't find out why it was not working. Finally, I ...

Drupal 6 and the  comment

An Axe to Cut Trees

The  comment has been used by Drupal to seperate the part of the text to show as a summary of your post and the rest.

That summary is often used on your front page, list views, etc.

The problem is that at times it breaks the editor. Something goes wrong and you just can't edit the post anymore.

To fix the problem, remove the break. Oh! But...

Effectively, you can't edit the post if it has a break so you can't edit the post to remove the break. At least not easily. That is, you could copy the part before the break and then edit and then paste. If you have ...

Jetson Xavier AGX with a Raspberry Pi showing the ports

First Boot

If you're here because the first boot didn't work, the system showed a message in the console saying:

a start job is running for End-User configuration after initial OEM installation

Then you most certainly have the network connected. The Jetson will not start if there is a chance that it is connected to the Internet and thus could let someone from the outside connect to the board unless you already setup a user account with your very own user name and password.

This is done like this because of a new law in California which now forces people to enter a ...

You need just one port to access a computer...

Here I have a table of 13075 ports that hackers have been trying to access on one of my servers in one week. Many are well known ports. Most are rather random... This clearly shows you why you want to have a firewall properly setup on your computer. If you run any local services (all computers do) then hackers can connect to them unless you block them with a strong firewall setup.

For sure, if you see a port or service name that you recognize (that runs on your computer), then know that anyone on the Internet will be able to connect to it if you do not have a firewall in place. If ...

The control bar with "Switch to Draft" / "Saving ..."

Today, while working on an article about black holes, I experiences this Wordpress problem where my page was stuck saying that it was being saved. Interesting since I was not kicked out (logged out) and other features still worked in other pages of the website I had opened.

I'm not totally what happened, but I was able to open the post in another tab (i.e. right click on the Wordpress logo at the top-left and select "Open in a New Tab" then navigate to your posts and click on the one which is currently stuck) and it told me that there was a newer draft than the current ...

How to setup a Linux firewall

Firewall prevent unwanted accesses to connected computers.

Introduction

If you setup a Linux box, you want to setup a firewall before you connect your computer to the Internet. If you are setting up a remote server, it should only have the SSH port open. Connect to it, setup the fire, then only install the other servers and open ports as required (and only ports that need to be connected from the outside.)

Any port that you open without the firewall already setup is at risk. You may want to install PHP and along will come a database which may open a port to the Internet. Something that you just don't want to happen.

Setup Firewall

To ...

My Pi 3 running on my laptop.

Preparations

Well, that was a bit of work and I don't have all the answers yet, but I was able to setup the WiFi network on my Raspberry Pi 3.

The steps are numerous because it did not work on my first attempt!

First of all, if you have MAC addresses firewalls and similar on your network, you want to check on that first and open the door to your Pi. I have such on my Belkin WiFi Router and on my main server so anyone can't just connect to my systems.

To see the MAC address of the Pi 3 WiFi, all I had to do is:

ifconfig
...
wlan0 ...
    ether 01:23:45:67:89:AB ...
...

Introduction

I have to install Jira on two new VPSes so I wanted to have notes about the various tools that I need to install to make it all work.

The list should also work on your other Linux systems, such as Debian, Fedora, RedHat, etc.

This is not a replacement for the installation instructions found on the Atlassians website. It is complimentary so you can quickly get it installed on your servers. The problem being that usually you just do apt-get install <something> (on Debian/Ubuntu) and all dependencies get installed automatically. With Jira, since they only offer a ...

Unfreeze your Mouse when it Froze

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Main Menu

Using BIND as a Master and a Slave simultaneously

First Boot

Introduction

Setup Firewall

Preparations

Introduction