HKDevTips

To keep your prompt (PS1) with color shown in tmux screen, add the following property in .bashrc : force_color_prompt=yes

I will try to create a docker container with the simple flask application created some times ago. First, I create a shell script for starting the flask application, namely "boot.sh": boot.sh #!/bin/sh export FLASK_APP=simple.py flask run --host 0.0.0.0 Second, we need to create a requirements.txt file: requirements.txt flask == 1.1.1 Actually you can run the following to get the requirements.txt: pip freeze > requirements.txt Third, together with the simple.py file created in the  simple flask application , put those 3 files in an "app" directory: app/    - boot.sh    - requirements.txt    - simple.py Forth, create a Docker file outside the app directory: Dockerfile FROM python:3.6-alpine WORKDIR /home/app COPY app/ ./ RUN chmod +x ./boot.sh RUN pip install -r requirements.txt EXPOSE 5000 ENTRYPOINT [ "./boot.sh" ] Buil...

Just wanna to create a very simple Flask application in a single python source file: simple.py from flask import Flask application = Flask( "simple" ) @application.route ( "/" ) def index (): return "Hello World" To run this Flask application, run the following: export FLASK_APP=simple.py flask run If you want to put this application in a Docker container, you need to bind to 0.0.0.0: flask run --host 0.0.0.0 Now, navigate  "http://localhost:5000" to see the word "Hello World" displayed on the browser.

To enable navigation on tmux splitted pane using mouse In tmux environment, do the following: Ctrl-b Type :setw -g mouse on Done, try to switch your tmux pane with mouse. Note: To make this setting persistent, save this line in .tmux.conf : setw -g mouse on

To assign locale in moment.js, we can use the following:      moment.locale("en") It will returns "en". However, if you assign an unaccepted locale to it, it won't update its value. For example:      moment.locale("zh") It still returns "en", since "zh" is not an accepted locale for moment.js. Up till now, moment.js accepts:      zh-hk      zh-tw      zh-cn Reference:  momentjs

There are many possibilities for QGIS to hang / freezes while editing features. But for my experience, I found it often hangs when using a Shapefile layer. To minimize this kind of problem, I tried to use other feature format (e.g. SpatialLite). And the problem is relieved to some extent. Have a try and let me know if it helps or not.

To count the number lines of files / stdout in Linux, we uses "wc -l" to achieve. In Windows, we use the following instead: find /c /v "" For example, suppose we have a file "sample_file.txt" and we want to know the number of lines of that file, we can perform the following: type sample_file.txt | find /c /v ""

When you create table class using flask_sqlalchemy (the Flask extension for SQLAlchemy), it can maps the modal class to a proper table automatically. This is cool but if you have a table name with underscore (e.g. MY_SAMPLE_TABLE) and you name your model class with the underscore ('_') as usual, you will find SQLAlchemy will map your table name as something the following: "MY__SAMPLE__TABLE" Each single underscore (_) with becomes a double underscores (__). This is annoying and you might believe this is a bug, but in fact you can resolve this issues by naming your table class using the PEP8 naming convention, and named your class as: class MySampleTable(db.Model):      field_id = db.Column(db.Integer, primary_key = True)      field_data = db.Column(db.String(200)) The the SQLAlchemy will map the MySampleTable class to table name as "MY_SAMPLE_TABLE" correctly. For more information about PEP8, click here for details.

Job with LEGO + IT, what else I can asked for  ?

Installation Prerequisites Python 2.7, 3.5 or above Oracle Client / Oracle Instant Client "Basic" or "Basic Light" libaio / libaio1 package Installation  Reference cx_Oracle Installation guide Sample Python Code import cx_Oracle # Make DSN address. Real values for host address, port and service name were replaced by '<>'. dsn = cx_Oracle.makedsn('<host_address>', '<port>', service_name='<service_name>') # Connect to DSN orcl = cx_Oracle.connect(user='<username>', password='<password>', dsn=dsn) # Get cursor cursor = orcl.cursor() # Execute SQL statement cursor.execute('<SQL SELECT STATEMENT>') # Fetch result data = cursor.fetchone()

By default, you just can't send F10 to Ubuntu Terminal's curses program. This is because F10 is being captured by Terminal.app already. A quick workaround is to use "ESC 0" to simulate sending F10 inside Terminal.app. Reference

To customize application icon in Ubuntu: Create a .desktop file in ~/.local/share/applications/ e.g. /home/user/share/applications/<application name>.desktop Add the following content to the desktop file [Desktop Entry] Encoding=UTF-8 Version=1.0 Type=Application Name=ApplicationName GenericName=ApplicationName Icon=/home/user/application-icon.png Exec=/home/user/application/application-executable Categories=Category;Subcategory Done!

To remove unused packages in Linux, we will use the following software: deborphan gtkorphan (GUI based) rpmorphan References https://www.ostechnix.com/how-to-find-and-remove-unused-packages-in-linux/

To delete a list of files specified in a text based file list, do the following: > for /f %i in (files_to_delete.txt) do del %i Reference: https://superuser.com/questions/355584/how-to-delete-files-from-a-folder-using-a-list-of-file-names-in-windows

The following is a tutorial for exporting a text-based file list showing the difference between 2 directories (e.g. D:\DirA, D:\DirB): Step 1: Create a text-based file list for both directories > cd D:\DirA > dir /s /b /a:-d > file-list-dir-a.txt > cd D:\DirB > dir /s /b /a:-d > file-list-dir-b.txt Step 2: Use WinMerge to get the difference between the 2 file lists: Note: To display difference only, you need to set "View > Diff Context > 0 Lines". Step 3: Copy the difference from WinMerge and create a text file to store it.

In Ubuntu dock, to show applications in current workspace only, run the following command: $ gsettings set org.gnome.shell.extensions.dash-to-dock isolate-workspaces true References https://askubuntu.com/questions/992558/how-can-i-configure-the-ubuntu-dock-to-show-windows-only-from-the-current-worksp https://extensions.gnome.org/extension/887/workspace-isolated-dash/

When you run your springboot application in IntelliJ idea Community Edition having the following error, you can try the solution below to solve the problem. Error "Failed to introspect annotated methods on class org.springframework.boot.web.servlet.support.SpringBootServletInitializer" If your "pom.xml" has dependency with "provided" scope, you may have trouble when running your application in IntelliJ Idea Community Edition. <dependency> <groupId> org.springframework.boot </groupId> <artifactId> spring-boot-starter-tomcat </artifactId> <scope> provided </scope> </dependency> Some suggests that you can change the scope from "provided" to "compile". Here is another solution for this issue: In your "Run/Debug Configurations", check "Include dependencies with 'Provided' scope". Then you can run the application from IntelliJ Idea Co...

For reference: # data - image bytes im = Image.open(BytesIO(data)) I =  numpy.asarray(im) print("I type:", type(I), "I shape:", I.shape) >> I type: <class 'numpy.ndarray'> I shape: (512, 512, 3)

The     apt-daily.service   makes users feel very slow when running at startup. There is a workaround to delay its execution after system boot up: Do the following:  sudo systemctl edit apt-daily.timer  And paste the config to the config file:  # apt-daily timer configuration override   [Timer]   OnBootSec=15min   OnUnitActiveSec=1d   AccuracySec=1h   RandomizedDelaySec=30min  References: https://askubuntu.com/questions/800479/ubuntu-16-04-slow-boot-apt-daily-service https://ubuntu-mate.community/t/shorten-boot-time-apt-daily-service/12297

It just crashed with segmentation fault. Display card tested: Radeon RX 550, Intel UHD Graphics 630 From  https://androidstudio.googleblog.com/2019/09/emulator-2920-stable.html , the OS may crashes with incompatible Vulkan drivers.  Temporary rollback to emulator 29.1.12-5839083 as a workaround.

Syntax     VBoxManage modifyvm "VMS Name" --biossystemtimeoffset -ms    Note:    ms - milliseconds For example     VBoxManage modifyvm "VMS Name" --biossystemtimeoffset -86400000

Just finding some resources for learning about Kalman filter, seems it is a very useful technique which applicable on a lot of different areas. References: https://blog.maddevs.io/reduce-gps-data-error-on-android-with-kalman-filter-and-accelerometer-43594faed19c

For Python users, there is a conflict between "pandas 0.25.0" and "pandas-datareader 0.7.0" . If you do an "from pandas_datareader import data" , you will got a conflict:     "ImportError: cannot import name StringIO from pandas.compat" To get rid of this issue, use "pandas 0.24.2" + "pandas-datareader 0.7.0" instead.

Sometimes in dual boot system (Windows / Linux), the NTFS partitions might have some problem causing the Linux mounted the NTFS partitions as read-only. To solve this problem, one might try following to see if it works: Step 1: Unmount the partition first This can be done via Disks application OR command line: e.g. umount -v /dev/sda1 Step 2: Run ntfsfix on the target partition e.g. sudo ntfsfix /dev/sda1 If the command is successful, the following output should be shown:   Mounting volume... The disk contains an unclean file system (0, 0).   Metadata kept in Windows cache, refused to mount.   FAILED   Attempting to correct errors...    Processing $MFT and $MFTMirr...   Reading $MFT... OK   Reading $MFTMirr... OK   Comparing $MFTMirr to $MFT... OK   Processing of $MFT and $MFTMirr completed successfully.   Setting required flags on partition... OK   Going to empty the journal ($L...

Just a note for encoding URL in NDEF message, the NDEF record should user TNF_WELL_KNOWN as its TNF. And NDEF record type should be RTD_URI. And the first byte could be encoded for different protocols (e.g. 0x01 = "http://www", 0x02 = "https://www", etc. References: Beginning NFC Professional NFC Application Development for Android