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Out there, in the wild exists a lot of different authentication schemes or methods however one of them which is relatively popular because it’s implemented in most popular browsers at the moment, has this one peculiar “bug” in its specification - you cannot use a colon (’:’) in the username field. If you have ever seen a window such as this: Then that website is probably using HTTP basic auth and you must not use a colon in your username on that site because simply you would not be able to do that. ...

Are you working with git repositories in which a lot of code churn is happening? For example, do you have a repository with Puppet hierarchical data and there are a lot of pull requests where code is just being moved around between layers of hieradata? diff(1) ordinarily only differentiates between added and removed lines with green and red colours (certainly the user controls what are actually those colours) however git-diff(1) recently, at the end of 2017, got a new functionality where text that is just moved around can be highlighted in different colours. This is my case and this feature was a godsend because I did not want to spend a lot of time reviewing the syntax side of things if the hieradata is just being moved. That is why I wanted to share it with you so that it could help you out and perhaps someone has some even more good tips on how to make the reviewing process more effective. ...

If you have not known before, scanf(3) and fgets(3) are both functions intended for reading something from standard input and doing something with the result - in the former case it is interpreted and the results might possibly be stored in specified arguments and in the latter case the result is simply put into a buffer. The first one is commonly recommended to beginner C programmers for reading something from the user and parsing it. However, it should be avoided mainly because it is very error-prone and it is difficult to understand how it actually works for new people. Instead of scanf(3), sscanf(3) should be used in combination with fgets(3). That way, you can easily guess in what state your standard input stream is after using those functions and you get other benefits. Let me give some examples and explain more. ...

I see time and time again this myth that programming languages have varying speeds perpetually peddled in various discussions between programmers in different IRC channels, forums, and so on. Some people think that, for example, C is much, much faster than Python. And a few of them go even further - they argue that C is a language that is “close to the metal”. Well, let me tell you. The code that you write in C is actually dedicated for a virtual machine that can eat that code and spit out assembly which roughly does the things that it is supposed to according to the C language standard. Why roughly? Simply because that virtual machine is poorly defined and it has a lot of undefined behaviour. This opposes our original argument that C is “close to the metal”. How could real hardware be poorly defined? Could it be that if you executed a certain instruction one time it would do something completely different, that was not mentioned at all in the CPU manual? Well, the answer is obviously no. Nobody would use such computers. ...

You could probably find “Code Complete” by Steve McConnell in any of the top 10 lists of books recommended to read for all programmers. I recently finished reading that book too. I have to confess that at times the tips and knowledge in there was a bit too basic and fundamental but, on the other hand, I also think that it has a lot of golden nuggets of knowledge. While reading it, I was writing down notes after every section. Essentially, they were three/four ideas that I thought were the most important in each section. Sometimes, they were paraphrased from the conclusions of each section written by the author himself. In other cases, I summarised them myself, in my own words. ...

You may currently have this pipe-line in your CI/CD process that involves running ovftool directly on your ESXi host so as to deploy an OVA appliance directly from it and with as less overhead as possible as in this tutorial on virtuallyGhetto or you could have picked up some tips about running ovftool on ESXi from this article that I wrote some time ago. However, that is certainly not the best solution for many reasons. For example, if the input is not sanitized in some location(-s) then it becomes trivial to execute any command on the ESXi host. Thus, instead I recommend you to use a tool like Terraform to save your infrastructure as code in a Git repository, for example. With the 1.x version of the Terraform’s vSphere provider you can implement such pipe-line in Terraform as well. ...

Unfortunately but the specter of Internet censorship has finally came to Lithuania a few years ago. It was rampant already in some European countries but I never thought that it would come to Lithuania as well. I thought that this country was different… nope, it started to slowly transform and become like others in terms of Internet censorship as well. History As far as I can tell everything was fine up until around 2008, 2009. It all began when on 2010 July 8th a court in Lithuania, Vilnius satisfied a lawsuit by which foreign gambling companies such as “bet365 Ltd.” and “Unibet International Ltd.” were blocked from doing their business in Lithuania. Accordingly, their websites must be blocked, the court said. The decision was appealed and the court case dragged further into the future. ...

Recently I ran into an issue where this, for example, code fails: import os os.rename('/foo/a.txt', '/bar/b.txt') Traceback (most recent call last): File "", line 1, in OSError: [Errno 18] Invalid cross-device link The documentation for the os module says that sometimes it might fail when the source and the destination are on different file-systems: os.rename( src, dst, *, src_dir_fd=None, dst_dir_fd=None) Rename the file or directory src to dst. If dst is a directory, OSError will be raised. On Unix, if dst exists and is a file, it will be replaced silently if the user has permission. The operation may fail on some Unix flavors if src and dst are on different filesystems. If successful, the renaming will be an atomic operation (this is a POSIX requirement). On Windows, if dst already exists, OSError will be raised even if it is a file. ...

Introduction Let us say that you are using an vSphere (VMWare vCenter + one or more ESXi servers) environment in your company and you are creating virtual machines pretty often. Obviously you are familiar with the virtual machines template functionality but where could you get the templates? Well, one of the options is to look for them somewhere on the internet but that is not a very reliable thing to do since you have to trust a third-party to provide these to you. Most, if not all, operating systems distributors do not provide a VMWare template for their operating system. For example, Canonical only provides Ubuntu in a form of an ISO file. Thus, you have to change your approach and make the templates yourself. However, doing that manually that is tedious and very menial so you will look for solutions to this problem. Packer is something that solves this problem. ...

Intro Did you know that in Python 2.x you can do the following? $ python2 Python 2.7.14 (default, Sep 20 2017, 01:25:59) [GCC 7.2.0] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> True = False >>> False False >>> True False >>> not True True >>> True == False True >>> True != False False How can it be that not True is True and True is equal to False? Why is it even possible to do this? Isn’t what is True and False in the language defined to be constant and unchangeable? What sense does it make to change the meaning of what is True and what is False? In any way, to fix this bug in the matrix, do this: ...