Computerhilfen tech-tips

The online retailer Pimoroni offers a small and suitable active cooler for the Raspberry Pi 4: the Pi Fan Shim. It is assembled very quickly and plugged onto the GPIO ports of the Raspberry: You can still use the GPIO ports with the fan attached! The front GPIO ports have remained the same since the first Rasbperry Pi, so the fan also fits on the Raspberry Pi 3 or 2.The small fan is especially useful on the Pi 4: it can reduce the temperature of th... Read more...

The nano Editor is a small and popular text editor for Linux and the Raspberry Pi. It is usually included in the Ubuntu and Debian (+ Raspbian) installations and is a replacement for the vi Editor. To open a file with the nano editor, enter this command in the console:nano my-file.txtOr, to have super-user rights, type:sudo nano my-file.txt Important Nano commandsCTRL + O: Save fileCTRL + X: Close fileSTRG + W: Sear... Read more...

If your PC's mouse suddenly stops working, there can be many reasons. No matter whether the mouse is connected to the computer with a cable or sends it's movements wireless, there are numerous reasons why the mouse refuses to work. Here we have put together 5 tips to help you activate your mouse again! Mouse doesn't work: Check hardware!1: Cable connected?If the mouse is connected to the PC with a cable, you should first check whether th... Read more...

If you want to append elements to the current document using Javascript, an error may occur. This happens if the script is executed before the document is completely loaded. If you want to append something to the DOM with the function appendChild(), the Chrome Browser will show this error message:"Uncaught TypeError: Cannot read property 'appendChild' of null"or:"Cannot call method 'appendChild' of null"Read more...

Is my device waterproof? The IP protection class is often specified for cameras, mobile phones and many outdoor devices such as wall outlets or Bluetooth speakers: This will tell you whether the device is only protected against splashing water or is even waterproof. Nevertheless, the information must be taken with caution: All openings must be closed tightly with the protective caps that are often provided.In addition, the protection class usually ref... Read more...

Normally one minute is the smallest unit to run a cronjob. But if you need the automatic execution of programs or scripts more often, you can use a trick: This way you can execute a script every 30, 15 or 10 seconds and not only once per minute!Cronjob once per minute:* * * * /home/user/cronjob.shCronjob once per hour1 * * * * /home/user/cronjob.sh Run a Cronjob every 30, 15 or 10 seconds!While the cronjob can be used by default... Read more...

Lynx is a small and practical text browser: It is available for Linux and Raspbian among other systems and can also be started from the command prompt. It then displays web pages, but without images. This can be useful, for example, to execute scripts on your own web server or in the Smart Home. It can also be used to easily load data from web pages and extract the content without having to open the page in a "big" browser like Firefox.lynx https://w... Read more...

The w3m browser is a small and free text browser for Linux, which is very easy to use. Unlike the Lynx browser, you can also enable the meta refresh functionality in the browser: This allows w3m to follow meta redirections on a website. This can be useful to execute scripts on your own web server or reload them automatically. Installing w3mIf the browser is not yet installed, this is usually done via the package manager. Under Debian, Ubuntu... Read more...

Javascript can be used to quickly count the length of a string: This works similar to the strlen() function in PHP. So you know if a string contains 2, 3 or 255 characters.var string = 'this is a string';var strlength = string.length;The function to determine the length of a string with Javascript is called "length": To determine the length of the string, simply append the function to the string variable. The variable "strlength" in the examp... Read more...

PHP comes with the "striptags" function, with which you can easily remove all HTML commands from a text. In Javascript there is no command for this, but you can do the same with a little trick! This is important, for example, to process a text further, or just to count words and letters. Javascript: Remove HTML commandsJavascript does not have its own function to delete HTML commands from a value or variable. But that doesn't matter, you ... Read more...