openspace command convention

Quick note to self - when we want to use the built-in fadeIn or fadeOut commands, we can't use the name of the object as seen in the info tab - like Scene.Moon here,

We will get errors like
Error when calling script 'openspace.fadeIn': Could not find property 'Scene.Moon.Enabled'

Checking the script log, we need to append .Renderable to that name, like

openspace.fadeOut("Scene.Moon.Renderable", 5)

tumblerd prevents disk from being ejected on Linux

When trying to eject a USB external disk, a message along the lines of "process tumblerd is currently using the disk, eject anyway?"

https://duckduckgo.com/?q=what+is+tumblerd+which+is+keeping+disk+from+being+ejected+on+linux&ia=web

Since I had a very large number of images on that drive, and I had just saved an mp4 file onto the drive, tumblerd was probably creating thumbnails for all of the multimedia files. So, did 

killall -HUP tumblerd

and then the disk could be ejected.

OpenSpace session recording "save frames" crash

On my Lenovo ThinkCentre M93 machine with an NVidia GTX1050 graphics card, OpenSpace session recording playback with "save frames" was crashing after a few hundred frames being saved. Each frame was taking around 1000 to 1500 ms for 4096x4096 frames.

According to Claude.ai, the crashes might be due to CEF "being starved" between updates - and I submitted this fix as an issue on the OpenSpace repo.

Claude suggested workaround was in SGCT.

// sgct/src/image.cpp

png_set_compression_level(png, -1);  // changed to:

png_set_compression_level(png, 1);

As the comment just above that line says, -1 sets the compression level to default, which seems to be 6. Setting this to 1 made the frame export only 300 ms per frame (3x faster) and also fixed the crashes - so CEF was not "being starved" of updates.

The increase in file size was not much, 4 MB increased to 5.1 MB for a typical frame.

Another change I made before exporting again, was to close all other windows and apps like the Edge Browser, which I had used earlier for triggering the exports - now OpenSpace has some checkboxes in the export settings which allows us to hide the UI while exporting, so we don't need to trigger the export via a web browser.

Edit: No, the problem is not solved. No crash when saving frames for this recording, ts_003_moon_to_Earth.osrectxt

but crashes after a few hundred frames when saving frames for this recording, ts_002_india_rotate_zoom.osrectxt

So my current workaround was to split the recording into multiple smaller recordings.

downloading from a server via http (no SSL) with auth

Downloading some planetarium files from a server in Sweden, which had password protected directories but no SSL (no https) - 

1. Directly downloading via the browser - slow, prompts us to "Keep" or delete the file every time due to being downloaded unsecurely
   
   
2. Using aria2 - 
   
    aria2c -x16 -s16 --http-user=USERNAME --http-passwd=PASSWORD url
   
   Need ProtonVPN, since without it, http downloads are severely throttled to less than 100 kbps.
   
   
3. Better option, running 
   
   aria2c -x16 -s16 --http-user=USERNAME --http-passwd=PASSWORD -i urls.txt
   
   on one of our AWS servers - all the URLs get downloaded in a jiffy, then we can use Filezilla and download to our local machine over sftp without throttling issues.

github 14 day traffic stats

Since github has a page which shows 14-day stats, like https://github.com/hn-88/OpenSpace-AppImage/graphs/traffic but which is behind the login of the user, I asked Claude to create a stats page for the traffic to all my public repos. The prompt is here, 

https://github.com/hn-88/hn-88.github.io/blob/master/stats/prompt.md

and the github traffic stats page is here

https://hn-88.github.io/stats/

The "clones" number is so high for the https://github.com/hn-88/OpenSpace-AppImage/ repo because of the multiple daily build workflows.

adjusting sound volume on Mac

Since I don't have an Apple keyboard, adjusting the volume on the Mac mini was not very straightforward. An LLM's advice seemed to be a bit sarcastic when taken in the context of how easy it should be versus the method suggested - 

Adjusting the volume using the menu bar is a simple and straightforward method. Here are the steps to follow:

1. Click on the Apple logo in the top-left corner of your screen.
2. Select "System Preferences" from the drop-down menu.
3. In the System Preferences window, click on "Sound."
4. Go to the "Output" tab.
5. Drag the volume slider to adjust the volume level.

On my machine, it was "System Settings" and not Preferences. And, there seemed to be a slightly faster way, which is clicking on the "Control Centre" in the menu bar - screenshot below - the "edit controls" button allows us to drag the icon into the menu bar, too.

interesting - No-AI chatbot

Interesting to see how chatbots can be programmed manually, without any AI - https://p5js.org/tutorials/criticalai4-no-ai-chatbot/

Via https://p5js.org/

Via https://github.com/hedbergj/sims-dev/blob/gh-pages/expanding-universe-2/index.html

using Blender to mask bright scenes

Using the same technique as in this previous post, but running on Blender 5 on Mac Mini, 3840x2160 video for Unseen Earth was being rendered at around 15 fps using the ProRES LT codec. Apparently Blender still doesn't have GPU accelerated output codec support, and this is one of the fastest codecs as suggested by ChatGPT. The ProRES LT can then be re-encoded as HEVC using the py-ffmpeg-warp presets. 

Some more tweaks used were:

• Multiple masks one atop another to darken extremely bright areas,
• Using Shift-D to duplicate and then K to cut the mask
• Using an adjustment layer to increase contrast for the base layer. 

close all Finder windows on Mac

It looks like Option+Cmd+w is the keyboard shortcut to close all windows of an app. Also, Finder has this method of Option+click on the File menu, which then shows a "Close all" menu item. 

A bit clunky in my opinion. And apparently many people moving from Linux/Windows to Mac have this problem, due to selecting a large number of files and hitting "Get Info..." like I did - MacOS then proceeds to open that many info boxes instead of showing a single window with cumulative info as on Linux/Windows.

Moodle custom reports not being emailed

One of our Moodle instances had this issue being reported, that some newly created custom reports were not being emailed as scheduled. 

The issue was that notifications - including email notifications - were disabled for "Custom report builder schedules" at https://ourserver.org/admin/message.php

After enabling email notifications now for this, "Custom report builder schedules" - the issue was reportedly resolved.

google workspace storage limits

At some point of time, Google Workspace has added a feature to admin.google.com where we can set individual users' storage limits on or off, or change the value on an organizational unit basis. Our current Google workspace now has this feature. One possible catch is that the on/off setting is inherited from the base organizational unit. And it also seems to allow certain users to use 146% of their quota!

pdfs - make smaller - split or join

There was a requirement to 
1. Make some pdfs smaller than 200 kB to enable uploading on a govt. website
2. Split some pages of the pdf into separate documents.

I used pdfsam - https://pdfsam.org/download-pdfsam-basic/ - to do the separation and merging, 

and the online tool

https://www.adobe.com/acrobat/online/compress-pdf.html

to compress the pdf size.

troubleshooting dot net server crash on AWS

First, checked if the AWS dashboard has any troubleshooting info for me. But "This user does not have permissions to view AWS Health events" - so I wouldn't get much help from it. Used my earlier post on investigating another Linux server crash as well as ChatGPT for going step by step.

ChatGPT suggested these,

dmesg -T | grep -i oom

journalctl -k | grep -i oom

which had no results. No out-of-memory events seen with those commands.

du -sh /var/log showed 4 GB of journal

journalctl --disk-usage

also showed nearly 4 GB of current and archived logs.

But the system had enough hard disk space left, 

df -h

showed around 30% remaining for the OS disk. 

Checking authentication log with

tail /var/log/auth.log -n4000 | more

found an entry

2026-01-25T14:38:58.186744+05:30 ip-10-0-0-73 systemd-logind[600]: New seat seat0.

But ChatGPT said that's normal, this is apparently done for each login.

Then, copy-pasting the lines just before the crash from syslog, using T13 since the crash was around 13:30

sudo cat  syslog | grep T13 > /home/theadminaccount/syslogsnippet.txt

ChatGPT immediately found the issue. 

ourtestapi.service: Scheduled restart job, restart counter is at 101203

and the reason the service was failing was

The application '/home/thepath/www/ourapi/ourtest.dll' does not exist.

Stopped the service, disabled it, and deleted it from /etc/systemd/system

sudo systemctl stop ourtestapi

sudo systemctl disable ourtestapi

sudo rm /etc/systemd/system/ourtestapi.service

Additionally, as ChatGPT suggested, set up some limits for journalctl's logging by editing

/etc/systemd/journald.conf

and uncommenting these lines and adding values for them - under

[Journal]

SystemMaxUse=900M

SystemKeepFree=1G

RuntimeMaxUse=100M

MaxRetentionSec=30day

and restarted,

sudo systemctl restart systemd-journald

Also vacuumed (removed archived logs) with

sudo journalctl --vacuum-size=3000M

(0 bytes removed - archives were smaller than that)

sudo journalctl --vacuum-size=300M

(500M of archives were removed.)

see who has signed an app on MacOS

Via https://www.youtube.com/watch?v=1UDUtO7LY0k

 Apple Menu > About this Mac > More info button > (Search for System Report on left-hand panel)

In System Report, click the System Report button, then Software > Applications on left-hand panel.

Scroll down to the app in question.

Our self-signed OpenSpace builds show up as "Unknown". Sheepit Mac client also shows "Unknown", so there is a chance that I can edit the manifest of the app to run a script on double-click in order to allow the Mac build to run with a double-click on the app file.

allowing a non-root user to restart a service on Ubuntu Linux server

As described by ChatGPT, the preferred method was to create sudoers rules for the relevant service(s).

sudo visudo -f /etc/sudoers.d/ourapi

and inside that file, write

deployuser ALL=NOPASSWD: /usr/bin/systemctl restart ourapi.service, \

                         /usr/bin/systemctl start ourapi.service, \

                         /usr/bin/systemctl stop ourapi.service, \

                         /usr/bin/systemctl status ourapi.service

where ourapi.service is the service and deployuser is the non-root user.

Here, we double-checked the location of systemctl using 

which systemctl

After doing this, on logging on as deployuser, we can do things like

sudo systemctl start ourapi.service

where it will prompt for deployuser's password and then carry out the command.

But a caveat - we need to type exactly the same command as mentioned in the custom sudoers file - even equivalent commands like

sudo systemctl start ourapi

will not work unless we add that to the sudoers file also.

Azure supported VM sizes

Some Azure VM sizes become unavailable in some regions - case in point, after upgrading to 16 GB RAM for a day, I could not go back to the B-series 8 GB RAM VM in that Central India location (which had shown quota limited before I stopped it). Went back to a slightly more expensive D2asv4.

Edit - I had noted on 7th Jan that the size was Standard B2as v2 - vCPUs = 2, RAM = 8 GiB - and this was "insufficient quota" in Central India at the moment. It is Rs. 2998 per month. 

We then temporarily changed to D4as_v4 for a few hours, which is 7.5k per month. Stop the VM, change the size and then start the VM. And after the work was done, B2as v2 was not available, so we went to D2asv4 which is Rs. 3,778 per month.

some quirks of my KVM setup and Apple keyboard layout

Currently using this product, 

HDMI KVM Switch 4 Port - 

there were some quirks which I had to work around. 

1. The Dell desktop running Linux Mint needed the USB keyboard to be mapped to it while booting, or else it would boot into Windows instead, even though the default boot sequence was set to Linux. Probably because the "fail-safe" boot option is different, when it beeps to indicate "No keyboard detected."
2. The KVM switch defaults to number 4 on power up, not number 1. So, the Dell desktop needs to be connected to 4 and not 1, for booting up without having to hit the KVM switch.
3. The Mac mini can boot OK without having the KVM mapped to it, but if we leave it on and not logged in, the login screen blanks and we can't get the screen to come back to life with the keyboard or mouse - we need to short-press the power button.
4. The Mac mini default keyboard mapping was showing the Indian rupee symbol ₹ instead of the backtick symbol ` for the key to the left of 1 (perhaps after the upgrade to MacOS Tahoe). Since I need ` for markdown on github etc, changed the keyboard layout to "US" from "ABC India" which was the default. For this, following this,
   chose Apple menu > System Settings, then searched for Keyboard in the sidebar. There, Input sources > Edit button, the small + button at the bottom left to add Input sources. Quite easy to miss.