Using pkg install atomicparsley works on Ubuntu based distros with apt-get install atomicparsley but not on Termux.
It gives the error: E: Unable to locate package atomicparsley.
That means that no one has ported it for termux yet. You can try compiling it yourself on device, or cross compiling it by following the instructions in the readme.
Another option is of course to convert this issue into a package request and see if someone else is up for the challenge to cross compile it.
Doing it myself is beyond me. How do I convert this issue into a package request?
pull request #1822
If you could test it that would be good.
https://github.com/its-pointless/its-pointless.github.io/blob/master/files/dists/termux/extras/binary-arm/atomicparsley_0.9.6_arm.deb
This is what happened when I installed the file you commented (the arm version):
$ pkg install ./atomicparsley_0.9.6_arm.deb
Hit:1 http://termux.net stable InRelease
Reading package lists... Done
Building dependency tree
Reading state information... Done
7 packages can be upgraded. Run 'apt list --upgradable' to see them.
Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'atomicparsley:arm' instead of './atomicparsley_0.9.6_arm.deb'
The following NEW packages will be installed:
atomicparsley:arm
0 upgraded, 1 newly installed, 0 to remove and 7 not upgraded.
Need to get 0 B/94.0 kB of archives.
After this operation, 217 kB of additional disk space will be used.
Get:1 /storage/emulated/0/Download/atomicparsley_0.9.6_arm.deb atomicparsley arm 0.9.6 [94.0 kB]
dpkg: error processing archive /storage/emulated/0/Download/atomicparsley_0.9.6_arm.deb (--unpack):
package architecture (arm) does not match system (aarch64)
E: Sub-process /data/data/com.termux/files/usr/bin/dpkg returned an error code (1)
So I installed the the aarch64 version instead and it installed.
Here's the error I get when using it:
$ youtube-dl "https://m.youtube.com/watch?v=m1PDqdLQMv8" -x --audio-format m4a --embed-thumbnail
[youtube] m1PDqdLQMv8: Downloading webpage
[youtube] m1PDqdLQMv8: Downloading video info webpage
[youtube] m1PDqdLQMv8: Extracting video information
[youtube] m1PDqdLQMv8: Downloading MPD manifest
[youtube] m1PDqdLQMv8: Downloading thumbnail ...
[youtube] m1PDqdLQMv8: Writing thumbnail to: Miss World 2017 Top 5 Question and Answer-m1PDqdLQMv8.jpg
[download] Destination: Miss World 2017 Top 5 Question and Answer-m1PDqdLQMv8.webm
[download] 100% of 5.77MiB in 00:00
[ffmpeg] Destination: Miss World 2017 Top 5 Question and Answer-m1PDqdLQMv8.m4a
Deleting original file Miss World 2017 Top 5 Question and Answer-m1PDqdLQMv8.webm (pass -k to keep)
[atomicparsley] Adding thumbnail to "Miss World 2017 Top 5 Question and Answer-m1PDqdLQMv8.m4a"
ERROR: "AtomicParsley": error: only position independent executables (PIE) are supported.
Steps to get this error in Termux:
pkg install pythonpip install --upgrade youtube-dlpkg install ffmpegyoutube-dl "https://m.youtube.com/watch?v=m1PDqdLQMv8" -x --audio-format m4a --embed-thumbnailarm version is also not PIE
Sorry bout that fix it in a bit
It looks like Atomic Parsley is currently available in Termux through Arch Linux PTRoot. This script is designed to install Arch Linux in just a few keystrokes. Tapping this link https://sdrausty.github.io/TermuxArch/setupTermuxArch.sh will transfer setupTermuxArch.sh to your device. Simply run bash ~/storage/downloads/setupTermuxArch.sh to install Arch Linux in Termux. To install use pacman -S atomicparsley and this will install Atomic Parsley on device.

You have to set the locale and stuff while setting up Arch after waiting for it to download a big file and decompress. For the simple script I have to download music from YouTube, this is overkill. However, I see the difficulties in making the package for Termux so I'm fine without atomicparsley if it's not possible atm. Feel free to close this I guess.
@neelkamath I haven't had a chance to take a closer look at atomicparsley itself in detail. Can you describe some of your favorite features?
@neelkamath
You have to set the locale
What you describe is automated into setupTermuxArch.sh if you want English. If you do want another language, you should specify it.
@sdrausty atomicparsley is required for the pip package youtube-dl to download the cover art while downloading YouTube videos. This is great for music.
As for the Arch Linux part, it's still overkill for my needs for atomicparsley. I'd rather just not use atomicparsley then.
@neelkamath thank you for describing atomicparsley. Hopefully, someone will come along and port it to Termux.
Iv already ported it...
does it not work?
oh
I checked a day after and it wasn't updated so I thought you'd followup when you fixed it
as a note, i have recently lost interest in android and prefer iOS so i'm deleting my termux scripts
i have seen many ppl use youtube-dl on termux though so it'd still be useful
Thanks to @its-pointless there is now an atomicparsley package available for installation!
Most helpful comment
Thanks to @its-pointless there is now an
atomicparsleypackage available for installation!