You will write:

p play test.mp3 from console on fedora

you will get:

mpg123 test.mp3

For:

p display invoice.pdf in fedora

evince invoice.pdf

For:

p convert en.mp4 to en.mp3

ffmpeg -i en.mp4 en.mp3

For:

p count all files in all first level directories here and list name of directories and amount of files inside

find . -mindepth 1 -maxdepth 1 -type d -exec sh -c 'echo -n "{}: "; find "{}" -type f | wc -l' \;

For:

p length in seconds of ar.mp3

ffprobe -i ar.mp3 -show_entries format=duration -v quiet -of csv="p=0"