BASH Template Promises Safer Scripts

Many bash scripts start out as something quick and dirty but then become so useful that they live for years, indeed sometimes seeing more use than our traditional programs. Now that you can even run bash well under Windows (although, you’ve always been able to run it there if you tried), there are even more opportunities for your five-minute bash script to proliferate. [Maciej] decided he was tired of always having to patch up his quick and dirty scripts to be more robust, so he created (and shared) his boilerplate template for scripts.

Probably most of us have at least some basic template we start with, even if it just our last script project. What’s nice about [Maciej’s] template is that he documents what’s going on with each part of it. It is also relatively short without a lot of excess stuff. Of course, you’ll probably customize it, but it is a great place to start.

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Does PHP Have A Future, Or Are Twenty Five Years Enough?

In June, 1995, Rasmus Lerdorf made an announcement on a Usenet group. You can still read it.

Today, twenty five years on, PHP is about as ubiquitous as it could possibly have become. I’d be willing to bet that for the majority of readers of this article, their first forays into web programming involved PHP.

Announcing the Personal Home Page Tools (PHP Tools) version 1.0.

These tools are a set of small tight cgi binaries written in C.

But no matter what rich history and wide userbase PHP holds, that’s no justification for its use in a landscape that is rapidly evolving. Whilst PHP will inevitably be around for years to come in existing applications, does it have a future in new sites?

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Linux Fu: Shell Scripts In C, C++, And Others

At first glance, it might not seem to make sense to write shell scripts in C/C++. After all, the whole point to a shell script is to knock out something quick and dirty. However, there are cases where you might want to write a quick C program to do something that would be hard to do in a traditional scripting language, perhaps you have a library that makes the job easier, or maybe you just know C and can knock it out faster.

While it is true that C generates executables, so there’s no need for a script, usually, the setup to build an executable is not what you want to spend your time on when you are just trying to get something done. In addition, scripts are largely portable. But sending an executable to someone else is fairly risky — but your in luck because C shell scripts can be shared as… well, as scripts. One option is to use a C interpreter like Cling. This is especially common when you are using something like Jupyter notebook. However, it is another piece of software you need on the user’s system. It would be nice to not depend on anything other than the system C compiler which is most likely gcc.

Luckily, there are a few ways to do this and none of them are especially hard. Even if you don’t want to actually script in C, understanding how to get there can be illustrative.

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Add Scripting To Your C++ Programs With ChaiScript

If you are writing a program that has a technical user base, it is a nice touch to make the program scriptable. In fact, you might want to do the hard work in a programming language and then use your scripting language to build out features. In theory, this should be easy. There are plenty of embedded scripting libraries and they provide some way for your code to access script resources and for script resources to access selected host variables and functions. If you use C++, one of the easier ways to do this is with ChaiScript.

ChaiScript is BSD licensed and — assuming your compiler supports C++ 14 — it is as easy as including a header file and making a few calls. There are no special tools or libraries required. The code is portable between operating systems, including both 32-bit and 64-bit Windows. It is also threadsafe unless you turn that feature off.
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Scripting Language Rapidly Develops A Clock

In the past, you might very well have started programming in Basic. It wasn’t very powerful language and it was difficult to build big projects with, but it was simple to learn, easy to use, and the interpreter made it easy to try things out without a big investment of time. Today you are more likely to get started using something like an Arduino, but it is easy to miss the accessible language and immediate feedback when you are doing simple projects. Annex WiFi RDS (Rapid Development Suite) is a scripting language for the ESP8266 that isn’t quite Basic, but it shares a lot of the same attributes. One example project from [cicciocb] is a scrolling dot matrix LED clock.

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Lint For Shell Scripters

It used to be one of the joys of writing embedded software was never having to deploy shell scripts.┬áBut now with platforms like the Raspberry Pi becoming very common, Linux shell scripts can be a big part of a system–even the whole system, in some cases. How do you know your shell script is error-free before you deploy it? Of course, nothing can catch all errors, but you might try ShellCheck.

When you compile a C program, the compiler usually catches most of your gross errors. The shell, though, doesn’t look at everything until it runs which means you might have an error just waiting for the right path of an if statement or the wrong file name to occur. ShellCheck can help you identify those issues before deployment.

If you don’t like pasting your script into a Web page, you can install the checker locally by visiting GitHub. The readme file there also explains what kind of things the tool can catch. It can even integrate with common editors (as seen in the video below).

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Reverse Engineering How A USB Switch Switches

[Daniel] found himself with a need to connect a single USB device to two Linux servers. After searching around, he managed to find an inexpensive USB switch designed to do just that. He noticed that the product description mentioned nothing about Linux support, but he figured it couldn’t be that hard to make it work.

[Daniel] started by plugging the device into a Windows PC for testing. Windows detected the device and installed an HID driver automatically. ┬áThe next step was to install the control software on the Windows system. This provided [Daniel] with a tray icon and a “switch” function. Clicking this button disconnected the HID device from the Windows PC and connected the actual USB device on the other side of the USB switch. The second computer would now have access to the HID device instead.

[Daniel] fired up a program called SnoopyPro. This software is used to inspect USB traffic. [Daniel] noticed that a single message repeated itself until he pressed the “switch” button. At that time, a final message was sent and the HID device disconnected.

Now it was time to get cracking on Linux. [Daniel] hooked up the switch to a Linux system and configured a udev rule to ensure that it always showed up as /dev/usbswitch. He then wrote a python script to write the captured data to the usbswitch device. It was that simple. The device switched over as expected. So much for having no Linux support!