The Linux Page

Help other users realize that everything is possible, especially avoiding Windows for their own personal use.

Welcome to The Linux Page


Fox Trot by Bill Amend. Click to enlarge.
Click to enlarge

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:

My Jetson TX2 see from the top, the area with the heat sink and the fan is the actual Jetson card.
(click on image to see 4K version in new window)

Introduction

I just received my Jetson TX2 so I had to test it!

First I needed to setup the network since by default it wants DHCP which I don't allow by default on my server.

Since it's running Ubuntu, I thought it would be dead easy, but I ran in two interesting settings I hadn't seen before.

Stop Eth0

When you are about to edit an interface, you probably want to first bring it down. If you forget to do this step first, you may have to reboot to get the status back to normal. So run this one:

sudo ifdown eth0

You ...

Whenever you create a page, you at times notice that your text goes bye bye without telling you anything about the reason why it would do that.

The fact is that there are many reasons why this can happen. The following is here to remind me of the various possibilities that I've bumped into over time.

Text Color

The first one that got me many times is the color of the text. If that color is set to transparent or the same color as the background, then you won't see the text.

What I do to test that quickly is go to the block where the text is expected to appear and change the ...

As I was checking some logs, I found the laundry list of a robot checking out one of my websites: 54 hits. As we can see, it checks many paths, some of which it checked 2 or 3 times (the first number in my list is a count).

3 /apple-app-site-association
1 /cache/iph.php
1 /dbss.php
1 /ecss.php
1 /function-sync.php
1 /inlos.php
1 /sph.php
1 /tip.php
3 /.well-known/apple-app-site-association
3 /.well-known/assetlinks.json
1 /wp-content/plugins/another-wordpress-classifieds-plugin/AWPCP.po
1 /wp-content/plugins/auto-attachments/a-a.css
1 ...

Long Exposure Photograph Showing Start Rotation

Bad Documentation (if you ask me)

When you looks at the document of logrotate, the first page about the settings shows an example as follow:

/var/log/news/* {
    monthly
    rotate 2
    olddir /var/log/news/old
    missingok
    postrotate
        kill -HUP `cat /var/run/inn.pid`
    endscript
    nocompress
}

Making your think that it's okay to have an asterisk in this way, right? PLAINLY WRONG!

The logrotate utility actually has no heuristic to detect whether a file was already rotated or compressed so with an asterisk, it will discover all the files in a folder and ...

Today I spent hours trying to find out why one of my find_library() would fail.

I fixed the search implementation, to make it cleaner as a result, which is not a bad thing, but the problem was a -D on a cmake call that would define the value ahead of time. That is...

There is the search I used:

find_library( ADVGETOPT_LIBRARY advgetopt
            PATHS ${ADVGETOPT_LIBRARY_DIR} ENV ADVGETOPT_LIBRARY
         )

This looks just fine and it should work, easy. I even added a test in my main CMakeLists.txt to see what would happen:

find_library( TEST_LIBRARY advgetopt
            PATHS ...

Today I needed to check a zone file to see why the IP address was wrong on one of my servers.

Sure enough, the IP was the old one (We switch servers about 9 months ago). Although once in a while I would get the right IP, the second name server still had the old IP. I thought the cache would be renewed more often than that, but I guess this is well optimized!

The error I made is not change the time info which means that the second name server never saw the change. This is just a domain name I redirect so I never noticed the problem before.

To check the cached file, though, I needed a way to ...

Functional Subscribe Form

Today I installed a simple mailing list builder on my Becoming an Internet Affiliate website. So simple that it creates a widget on the sidebar and that's it. So it's not going to be super persuasive, but I like it that way for some of my websites.

The plugin is called Mail Subscribe List. It's a free plugin making it particularly attractive. And it keeps the names and emails in your database (no third parties involved.)

The plugin offers a Widget that you can install in your sidebar. Go to

Appearance » Widgets

and then select the Subscribe ...

This happens on all websites. It's not specific to Wordpress.

However, this is when hackers are trying to gain access to your website. They do two or three things. First they choose common user names such as "admin" or your .com name (i.e. I have https://stargazerrock.com/ and they used "stargazerrock" as the username!) I saw "administrator" as well.

One way to protect your administrator account immediately is to change your username to something that they are not likely to guess. Say your surname is "giraffe", you could use that. Or even better, ...

Today I tested one of my Stargazer Rock blog pages and got a WSoD... Not the first time, but last time I fixed the problem by loading and resaving a PNG and changing an SVG to a PNG. Not the type of things I really want to do while bloging.

So I search into it, there is a plugin I use, called "Facebook Open Graph, Google+ and Twitter Card Tags" which attempts to load an image but only the first 32Kb. If that loads fine, then the author attempts to get the image dimensions and save that to the open graph meta data.

Somehow, some images will actually break that process because the ...

At times you have to prevent users from seeing files under a certain folder such as the /admin/ or /wp-admin/ folder.

The easiest way to at least avoid having Google index those pages is to add a Disallow line in your robots.txt file. For example:

Disallow: /admin
Disallow: /wp-admin

This is great and 99% of the time it does exactly what you want. Only once in a while a programmer does it wrong and places a file that should be searchable under such folders. For example, maybe someone placed a style.css file which is access by pages other than just pages under /admin. In that case, the ...

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