Blogs

Here you can find a list of all my blogs published here.

  • xcrun: error: invalid active developer path
    Mac is a nice computer for developing, MacOS and Apple can make your developer life a challange. After updating XCode - after all, why have a Mac when you do not develop iOS apps - it may happen that git stops working. Running git gives you: xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun Usual situation: it worked yesterday, today it is broken and you did nothing. Besides updating XCode. The problem occurs easily. When you update XCode, normally you also update the command line tools. In case the Apple App Store isn't giving you the option to update the command line tools, run the command xcode-select --install Output xcode-select: note: install requested for command line developer…
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  • PowerLAN in real life
    I bought a PowerLan adaptor to be able to connect to my private "server" (aka Raspberry PI) from the other side of the house via WLAN. Connecting the RP via WiFi wasn't an option: two far away from the signal, I'd need to install at least one additional repeater and then two RP are without wireless adaptor. The PowerLan adaptor supports up to 1.200 MB/s and let's me connect 3 devices directly. I won't even need to buy an additional switch. And 1.200 MB/s. In theory, this is FAST. In reality the setup is complicated. The two adaptors are in the opposite location of a not-so-small house, the electrical stuff and cables were installed some 40 years ago. Some things…
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  • UUIDD problem when running SAP NW ABAP inside Docker
    UUID is a good old problem when it comes to running SAP NetWeaver on Linux / SuSE. You have a problem when you log in to your SAP system and get an error message. The error message shows the root cause and solution: “The UUID daemon (uuidd) is not active (code 59999). Check SAP note 1391070.” Solution SAP NetWeaver isn’t meant to run in Docker. When the software was designed, Docker or event containerization wasn’t around (maybe SUN). NetWeaver assumes that it is executed inside a real Linux. And the Docker version of OpenSuSE isn’t 100% a real Linux. A lot of services you get “automatically” when installing OpenSuSE are not available. One of those is that the init.d system…
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  • Connect to NetWeaver ABAP instance running inside Docker
    This blog will help you to connect to your SAP NetWeaver ABAP instance running inside a Docker container. For how to get NetWeaver running inside a Docker container, please see my blog Docker for SAP NetWeaver ABAP 7.5x Developer Edition. SAPGui Open SAPGui and create a new connection. Give a name for the connection and click on tab Advanced. I use NPL Docker. Activate expert mode and give the correct connection String. Check to which port the message server port is mapped to by Docker. Inside the container, the port is 3200, and in my case, the external port is 32771. Therefore, the connection String is: Connection String: conn=/H/localhost/S/32771 Note: the port information is specified when you start the container.…
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  • Dockerfile for SAP NetWeaver ABAP 7.5x Developer Edition
    This blog will help you to run your own SAP NetWeaver 7.51 ABAP instance inside a Docker container. This work was inspired by the Dockerfile created by Gregor Wolf and hosted at bitbucket. The difference is that in Gregor’s version you download the NW ABAP installation files and when the container is build, you go manually through the installation. My Dockerfile assumes that you have downloaded the NW 7.51 ABAP installation files already and will automate the installation. Once you have downloaded the installation files from SAP you can make them locally available and create new Docker images / containers based on these, without having to download almost 16 GB again. And the installation script will run without prompting for…
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  • Enable Wake on LAN on Windows 10
    To be able to wake up your computer via wake-up-on-lan (WOL), you need to enable this feature in the BIOS and in the Windows 10 LAN adaptor settings. Configuration: BIOS Configuration depends on the BIOS of your computer. In my case, wake up on LAN is in the power on section and disabled by default. To use this feature, just enable it. Do not forget to save the change. Configuration: Windows 10 After activating WOL in the BIOS, you need to configure Windows 10 to allow the device to wake Windows. My test computer is a Lenovo Q180 running Windows 10 German. More information on how to activate WOL for this device can be found here. Go to Network and…
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  • Block access from country by IP in Apache
    In this blog I will show how you can block access to your Apache hosted internet services, forbidding access to a whole country. The access is blocked based on the IP address of a client. In case of a VPN where the user connects to a VPN server in another country, the user will still be able to access the site. The internet is a great to ensure freedom of speech. Anyone can raise his/her voice; use the information to be informed on what is happening in the world, let others know about something, share knowledge. You can do so by using a social site or by hosting your own site. The ease of access to information; be able to…
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  • Convert SVG to PDF
    Some time ago I registered for a virtual training. The training material was made available in a web app. No PDF or a downloadable version of the material. Not a big issue, as long as I had internet access and only wanted to read the material. Problems started when I tried to access the material without a stable Internet connection. Depending where I am online is not an option. Plus point for having training material in PDF format. I can print PDF, making it easier to learn: offline, annotate pages, mark words, easier to read for the eyes. While a cloud solution is good for the vendor, it’s not always a very good option for the consumer. Taking a closer…
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  • Install SAP Web Dispatcher on Docker using SWMP
    SAP Web Dispatcher is an important component in a SAP landscape. While have been treated as optional for many years and found mainly in SAP Portal scenarios, with the increase adoption of Fiori, having a reverse proxy in the landscape is becoming pre-requisite. While it’s possible to choose from a wide range of alternatives of servers for a reverse proxy, SAP`s Web Dispatcher is normally always the best fit in a SAP landscape. A question that sometimes arises is how to install Web Dispatcher. First you settle on what version of Web Dispatcher (WD) to install. SAP Note 908097 states that you should go for the latest version. “Version 7.49 is the recommended SAP Web Dispatcher version for all backend…
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  • Parallel download of files using curl
    In a previous blog, I showed how to download files using wget. The interesting part of this blog was to pass the authentication cookies to the server as well as using the file name given by the Content-Disposition directive when saving the file. The example of the previous blog was to download a single file. What if you want to download several files from a server? Maybe hundreds or even thousands of files? wget is not able to read the location from a file and download these in parallel, neither is curl capable of doing so. You can start the download as a sequence, letting wget/curl download the files one by one, as shown in my other blog. Just use…
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