Sunday, June 7, 2020

The Safe Way to test Thermal Runaway Protection on 3D Printers


  1. Disconnect the heater cartridge from the main board
  2. Start heating the hot end
  3. Expect machine to error out after ~10 seconds and shut down 

Thursday, May 28, 2020

Writing useful commit comments

Some thoughts on writing useful [concise, descriptive, contextual] commit comments. Applies to all SCM systems (Git, Subversion, etc.)

A properly formed Git commit subject line should always be able to complete the following sentence:

  • If applied, this commit will your subject line here
For example:
  • If applied, this commit will refactor subsystem X for readability
  • If applied, this commit will update getting started documentation
  • If applied, this commit will remove deprecated methods
  • If applied, this commit will release version 1.0.0
  • If applied, this commit will merge pull request #123 from user/branch
Chris Beam

Thursday, May 14, 2020

Don't name ANYTHING AUX, or NUL, or...

Further to my earlier post, I discovered 'aux' is not just a bad choice for folder names, it's bad for ANY file name on Windows!

Apparently back in the Dark Ages (1974 or so) when Bill Gates invented computers, the Interwebs and everything else digital, AUX, NUL, COM3, etc. were deemed names reserved for the OS, "magical files" if you will. That decision lives on through backward-compatibility (c'mon, 1974?! CP/M?! DOS?!?!?).

While working on my project, MS Visual Studio Code happily agreed to let me name a file"aux.yaml". Even though this ominous warning appeared, it let me continue once I appended "yaml" to the name:


 Everything went fine until I tried to add the file to the project's working copy in Subversion. For some reason, no matter how many times I pressed "Add..." in TortoiseSVN, the file refused to appear in the commit list, and failed to adopt its stroppy little blue plus sign in Windows Explorer.

Hmm, let's open it with Notepad++ to make sure the file is OK - nope, Notepad++ complained bitterly about the file when I tried to open it:



So at this point I figure the file was somehow corrupted by my attempts to add it or move it around in the Subversion working copy, let's just nuke it and start over:


OK this is definitely weird.

A few minutes googling produced the answer: open an admin command prompt and delete or rename the file. The command ren \\.\C:\path\to\file\aux.yaml auxiliary.yaml put everything right again - TortoiseSVN happily added the file, Notepad++ opened it with nary a whimper, and Visual Studio Code - well, let's just say it has it's own opinion on file names.

References:

How a 1974 bug still bites Win10 and Azure users

Monday, May 11, 2020

Windows error naming folder 'aux' - wat?!


Windows complained, unjustly I thought, when I tried to name a folder 'aux'. Turns out this is one of a number of restricted MSDOS device files:

CON, PRN, AUX, CLOCK$, NUL
COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9
LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, LPT9
LST (only in 86-DOS and DOS 1.xx)
KEYBD$, SCREEN$ (only in multitasking MS-DOS 4.0)
$IDLE$ (only in Concurrent DOS 386, Multiuser DOS and DR DOS 5.0 and higher)
CONFIG$ (only in MS-DOS 7.0-8.0)

Thursday, September 19, 2019

How to Get a Good Old Command Prompt from Windows Explorer in the latest Windows 10

Remember the ol' shift-click in Windows Explorer trick to open a command prompt from a folder?


Windows 10 since version 1803 (?) helpfully offers to open a Powershell prompt instead:


Which is great, if I want Powershell, which I don't. Apparently there's no way to revert or override this helpful 'feature', so I went around the side door - I shift-clicked to open Powershell, then typed "cmd" at the Powershell prompt, et voila, I get a good old command prompt in the folder:


Thursday, July 18, 2019

Neil Armstrong's first step happened on my 10th Birthday! Or did it?

Did Neil Armstrong's historic first step on the moon land on my 10th birthday? Let's see. NASA published a detailed timeline of the Apollo 11 mission, and with a little help from date/time conversion websites, and a confirmation that California did indeed observe PDT in 1969, I constructed this timeline of the highlights:

Apollo 11 Timeline

Event       PDT (UTC-7)     EDT (UTC-4)     UTC (GMT)       SAST (UTC+2)
                                                            No DST
----------- --------------- --------------- --------------- --------------
Liftoff     6:32 am          9:32 am        1:32 pm          3:32 pm
                                            Wed 16 July

Landing     1:17 pm         4:17 pm         8:17 pm         10:17 pm
                                            Sun 20 July

First       8:56 pm        11:56 pm    |    2:56 am          4:56 am
Step        Sun 20 July                |    Mon 21 July

My 10th     10:35 pm
Birthday    Mon 21 July

Lunar       10:54 am        1:54 pm         5:54 pm          7:54 pm
Ascent                                      Mon 21 July

Splashdown   9:21 am       12:51 pm         4:51 pm          6:51 pm
                                            Thu 24 July
                                             
I have a recollection of watching the landing on (black and white) TV, then looking out the window at the sky, thinking, "Wow, they are up there right now!". I don't recall if the Moon was visible during the day at that time.

Well, sadly, as I was living in Petaluma, California at the time, Neil's boot hit the moondust at 8:56 pm PDT on Sunday, July 20th, the day before my 10th birthday.

For a certain someone in Cape Town, however, it happened very early on her 10th birthday!

Wednesday, May 1, 2019

Perl - get the script path

# C:\Foo\Bar\my_script.pl

use strict;
use warnings;

use FindBin qw($Bin);

print "My script lives in $Bin\n"; # My script lives in C:/Foo/Bar


Note that there is no trailing slash, and Windows back-slashes '\' are converted to forward slashes '/'