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Needed to do a project in Java8, here’s how to install openjdk8: sudo add-apt-repository ppa:openjdk-r/ppa sudo apt-get update sudo apt-get install openjdk-8-jdk sudo update-alternatives --config java # select openjdk8 sudo update-alternatives --config javac # select openjdk8 sudo apt-get purge maven maven2 maven3 ...

Go to http://pypy.org/download.html and find the download link and wget/extract it. wget https://bitbucket.org/pypy/pypy/downloads/pypy3.3-v5.2.0-alpha1-linux64.tar.bz2 tar xfj pypy3.3-v5.2.0-alpha1-linux64.tar.bz2 Preferably move it to /opt/ or /usr/local/: sudo mv pypy3.3-v5.2.0-alpha1-linux64 /opt/ Install pip and virtualen...

First, go to https://dev.mysql.com/downloads/repo/apt/ and click “Download” button, on next page, copy the link that says “No thanks, just start my download.”, it should point to something like https://dev.mysql.com/get/mysql-apt-config_0.7.3-1_all.deb Use the link to wget the file. then sudo dpkg -i mysql-apt-config_0.7.3-1_all.deb Selec...

I ordered a ECS from Aliyun, it come without a (virtual) swap drive. Here are the steps to create one: sudo dd if=/dev/zero of=/swapfile bs=1G count=2 sudo chmod 600 /swapfile sudo mkswap /swapfile sudo swapon /swapfile A 2G swap space is created and activated. To make it available at next reboot: sudo vi /etc/fstab add this...

If you see something like this when you do webpack: ERROR in ./app/app.js Module build failed: Error: Couldn't find preset "es2015" relative to directory "/home/yourname" That’s becuase you have a .babelrc in your home directory but not in your project directory. To get rid of this error, either deleting the .babelrc in your home directory o...

I wanted to convert a SVG file to GeoJSON. Gdal command ogr2ogr is supposed to support these 2 formats. But when I tried it: $ogr2ogr -f GeoJSON circle.json circle.svg FAILURE: Unable to open datasource `circle.svg' with the following drivers. It then listed drivers that includes both geojson and svg. What’s going on? Turns out that gdal o...

update: Because of API change, the command line now should have additional ‘-f account_key.json’. The full example command is: $simp_le -d example.com:/var/www/sites/example_com/server -f key.pem -f cert.pem -f fullchain.pem -f account_key.json Let’s Encrypt entered public beta 2 days ago. It also happened that I have a SSL certificate that ...

Even though I promised myself I would blog more, I just cant think of what to blog. I learned a lot lately, but putting them in writings in a coherent manner is quite a challenge. These days my minds seems scattered around all over the places, there is clearly lack of focus and even priorities. I really should be taking a pause from time to t...