You can get the source for that command line tool here [1]. It's a single file C program that just uses stdio.h and stdlib.h and inputs from stdin and outputs to stdout, so should be easy to get working on anything that has a C compiler and a terminal with a simple "cc chord.c".
There's a little bit of documentation in this comment from a couple years ago [2]. There's a source link in that comment too, but that is to an older version. I added a couple more chord types later so use [1] instead.
Note: I'm not sure I got all the chord types quite right, so be sure to look at the notes it says are in the chord you asked for to make sure it got the right notes.
Check out the whole post that [2] was a comment on. There were several other people who also commented sharing guitar or music tools they had developed.
[1] https://pastebin.com/HKyKWHip
[2] https://news.ycombinator.com/item?id=23922951