Single and Double Quotes Question...

[manyoyo-co]

Question

Hello, I'm wondering why there are single quotes used around the filenames below except for in the final line, Adding thumbnail, when there are double quotes.

Just curious. Thanks.

[youtube] LzhlU8rXgHc: Downloading webpage
[youtube] LzhlU8rXgHc: Downloading video info webpage
[youtube] LzhlU8rXgHc: Downloading js player vflSXUoF7
[youtube] LzhlU8rXgHc: Downloading js player vflSXUoF7
[youtube] LzhlU8rXgHc: Downloading thumbnail ...
[youtube] LzhlU8rXgHc: Writing thumbnail to: Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.jpg
[download] Destination: Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.webm
[download]  24.0% of 15.75MiB at  1.49MiB/s ETA 00:08^C^X
ERROR: Interrupted by user
pi@AGX-O4:~ $ youtube-dl -i -f 'bestaudio' -x --audio-format 'mp3' --audio-quality '0' --add-metadata --embed-thumbnail https://www.youtube.com/watch?v=LzhlU8rXgHc
[youtube] LzhlU8rXgHc: Downloading webpage
[youtube] LzhlU8rXgHc: Downloading video info webpage
[youtube] LzhlU8rXgHc: Downloading thumbnail ...
[youtube] LzhlU8rXgHc: Writing thumbnail to: Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.jpg
[download] Resuming download at byte 3960926
[download] Destination: Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.webm
[download] 100% of 15.75MiB in 00:04
[ffmpeg] Destination: Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.mp3
Deleting original file Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.webm (pass -k to keep)
[ffmpeg] Adding metadata to 'Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.mp3'
[ffmpeg] Adding thumbnail to "Leonard Nimoy reads Ray Bradbury's 'There Will Come Soft Rains' from 'The Martian Chronicles'-LzhlU8rXgHc.mp3"

[dstftw]

This is just print output.

[manyoyo-co]

Thanks, @dstftw -- but is there any reason why the print output differs between 'Adding metadata' and 'Adding thumbnail'? Is the second command nested (?) within the first?

[dstftw]

One more time: this is just a print output, there is no relation between these two outputs.