BEGINNER for loop bash script using imagemagick command

1. First we make a make a circle 01:13

convert -size 81x81 xc: -fill black -draw 'circle 40,40,40,3' -fuzz 5% -transparent white black_circle.png

2. write a bash script in vim (I named mine im.sh) 02:50

#!/bin/bash
n=1000
for i in {150..1920..5}
do
convert -size 1920x1080 canvas:grey black_circle.png -geometry +$i+0 -composite oupt_$n.png &
((n=n+1))

done

3. make the script executable 08:56

chmod +x im.sh

4. run the script 09:23

./im.sh


5. now I want to combine all the images to make a video 10:34

cat *.png | ffmpeg -framerate 60 -f image2pipe -i - output.mkv

00:00 intro
01:10 command to make a circle
02:30 start vim
08:18 completed bash script
08:58 making the script executable
09:24 run the script
09:51 command to turn images into a video

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To my kids, love you very much.
This video took a lot longer than it needed to because I kept making mistakes. hopefully I can get faster and better. The reason I did such a simple bash script is, firstly, because I am learning, and secondly, I'm having problems with my animation programs. I have previously shown the segmentation fault I get from krita, I am also getting a segmentation fault when I use blender. Although I can use the programs to make images and 3d objects; when I follow tutorials exactly they don't work. The shortcut keys they say to use, don't work, the program crashes, things don't act the way the instructor says it should. So I want to understand these older programs where I can do things on my old computer without problems. Maybe this can also help others who don't have the money to go out and buy the latest stuff. Hope you are doing ok out there.