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January 12, 2025
Wireshark
Here's some notes on Wireshark, especially filtering results. You need to set an environment variable in a terminal, AND open the browser from that terminal: Then, you need to tell Wireshark...
ReadDecember 29, 2024
Kubernetes ConfigMap Values
Extract a Specific Key from a ConfigMap: You can use jq or yq to parse JSON or YAML output to get specific values. For example, to get the value of a specific key in a...
December 21, 2024
Command to Find a Command's Apt Package
Sometimes I type a command in linux and it's not found. I try to install it and it's not found. Often it will say what package you need to install, but when it doesn't it's usually something...
ReadDecember 21, 2024
Signal Handling in Three Languages
Signal processing in three scripting languages: Run: Run: Run:
ReadDecember 21, 2024
Command to Find a Command's Shared Libraries
Command to find out what shared libraries an executable needs: ldd /bin/bash eg
When I created a chroot test, I copied /bin/bash and then did the ldd, and it was not...
December 21, 2024
Python Instance Types
Python's gettype or instanceof is isinstance().
isinstance() can be used to check for a variety of object types in Python. Here are some common...
December 21, 2024
Hexidecimal Math
Note: this is not the "word" abc123. This is the number abc123 as represented in hexidecimal.
Each "place" is 16^<place>.
So abc123:
a...
December 21, 2024
Endianness and Hex Editor Values
Type "foobar" (no quotes) into a text file, open in a hex editor. 'b' will be hex '62' which translated to dec is '98', which is the ascii code for the letter 'b'. B's ascii code is 66, so the hex...
ReadDecember 7, 2024
Docker RUN v CMD v ENTRYPOINT
RUN - (buildtime) during image build, lines in a bash script to install everything for the image. Most Dockerfiles will have many of these. Each one creates a docker layer. It's a good idea to...
ReadDecember 7, 2024
Docker RUN v ADD v COPY
I was wondering why we needed specific commands like COPY, instead of just RUN cp file1 file2. Research, and a colleague, says there are two reasons:
Basically,...