MongoDB Updated 2025-07-16
List databases:
echo 'show dbs' | mongo
Delete database:
use mydb
db.dropDatabase()
or:
echo 'db.dropDatabase()' | mongo mydb
View collections within a database:
echo 'db.getCollectionNames()' | mongo mydb
Show all data from one of the collections: stackoverflow.com/questions/24985684/mongodb-show-all-contents-from-all-collections
echo 'db.collectionName.find()' | mongo mydb
Alphabet Updated 2025-07-16
Larmor precession Updated 2025-07-16
The equation is simple: frequency is proportional to field strength!
The best cycling map app Updated 2025-07-16
  • Google Maps download offline maps. This works very reliably, you can select the area you want to download. The only downside is that Google maps can't reliably show a route offline, and it does not contain national cycle route routes. Or those features are impossible for a software engineer to get working after trying for about 2 hours.
  • OpenStreetMap on browser with cycling layer: www.openstreetmap.org/#map=5/49.582/1.934&layers=C This is the best visualization of cycling routes I've found so far, contains both National Cycle Network and National Byway and a few others, and they are shown extremely clearly. But as a website it doesn't reliably work offline
  • the OsmAnd app for Android is the best offline free-ish OpenStreetMap viewer I've found so far. You only have to pay after reaching 5 region downloads, and it is very cheap if you want to do so. The cycle route view is not amazing, the routes are not so clearly marked and mixed with very similarly colored big roads, but with a bit of effort you can make them out. No routing though
  • I've heard Komoot can keep a predefined route (possibly auto planed) reliably offline, but haven't used it myself. I was not able to see National Cycle Route clearly marked anywhere on it
Previously it was unclear if there were any .org hits, until we found the first one with clear comms: web.archive.org/web/20110624203548/http://awfaoi.org/hand.jar
Later on, two more clear ones were found with expired domain trackers:
further settling their existence. Later on newimages.org also came to light.
Others that had been previously found in IP ranges but without clear comms:
  • 65.61.127.177: material-science.org
  • 212.4.17.61: tech-stop.org
  • 74.116.72.244 arborstribune.org
.org is very rare, and has been excluded from some of our search heuristics. That was a shame, but likely not much was missed.
Not in other sections:
Cell projection Updated 2025-07-16
One of several things that can stick out of a cell, e.g. flagellum or an axon.
Euro Updated 2025-07-16
Video 1.
The Euro Has Never Been More Problematic by Yanis Varoufakis (2018)
Source. Talk given at the Oxford Union. youtu.be/cCA68U3P_Z8?t=1288 describes the problem with the Uero a bit better.
Evil demon Updated 2025-07-16
Genesis block message Updated 2025-07-16
Inscription added by Satoshi Nakamoto on the Genesis block containing:
The Times 03/Jan/2009 Chancellor on brink of second bailout for banks
which is a reference to: www.thetimes.co.uk/article/chancellor-alistair-darling-on-brink-of-second-bailout-for-banks-n9l382mn62h wihch is fully titled:
Chancellor Alistair Darling on brink of second bailout for banks
The "Alistair" was slikely removed due to limited payload concerns.
Through the newspaper reference, the message proves a minimal starting date for the first mine.
And it hints that one of Bitcoin's motivation was the financial crisis of 2007-2008, where banks were given bailouts by the government to not go under, which many people opposed as the crisis was their own fault in the first place. A notable related stab is taken at Len Sassaman tribute.
We can extract the image from the blockchain ourselves by starting from: blockchain.info/block-height/0?format=json.
From that page we manually extract the hash 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f and then:
wget -O 0.hex https://blockchain.info/block/000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f?format=hex
xxd -p -r 0.hex
and that does contain the famous genesis block string:
EThe Times 03/Jan/2009 Chancellor on brink of second bailout for banks
The JSON clarifies that the data is encoded in the script field of the transaction input:
{
      {
         "script":"04ffff001d0104455468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73"
The extra E (0x45 in ASCII) in EThe Times is just extra noise required by the script, we can break things up as:
04ffff001d0104 45 5468652054696d65732030332f4a616e2f32303039204368616e63656c6c6f72206f6e206272696e6b206f66207365636f6e64206261696c6f757420666f722062616e6b73
where:
  • 54 is T
  • the 04ffff001d0104 part just doesn't show up on the terminal because it is not made of any printable characters.
The initial 04 is OP_RETURN.
TODO what is actual the meaning of the ffff001d010445 part? @defango twitter.com/defango/status/1642750851134652417 comments:
04ffff001d0104 is a hexadecimal string. It is commonly used in the Bitcoin network as a part of the mining process. Specifically, it is used as the target value for a block to be considered valid by the Bitcoin network.
This value represents the level of difficulty required for a miner to generate a block that meets the network's criteria. The first four bytes, 04ffff, represent the maximum possible target value. The next three bytes, 001d01, represent the current difficulty level
while the final byte, 04, is a padding byte. In summary, this value sets the difficulty level for mining a new block in the Bitcoin network.
TODO the output of the transaction has a jumbled script, likely just a regular output to get things going, can't be arbitrary like input.

Unlisted articles are being shown, click here to show only listed articles.