[Librarian1949]

I'm no MacOS terminal expert, I followed guidance and did:
nigelcrompton@nigels-iMac ~ % cd /Applications/calibre.app/Contents/MacOS/
nigelcrompton@nigels-iMac MacOS % ls
booklist.txt calibre-server ebook-meta lrs2lrf
calibre calibre-smtp ebook-polish markdown-calibre
calibre-complete calibredb ebook-viewer web2disk
calibre-customize ebook-convert fetch-ebook-metadata
calibre-debug ebook-device lrf2lrs
calibre-parallel ebook-edit lrfviewer
nigelcrompton@nigels-iMac MacOS % calibredb list --fields=authors,title --sort-by=author_sort --ascending --line-width=250 --separator=";" >booklist.txt
zsh: command not found: calibredb

What am i doing wrong, please ??
I'm on MacOS 11.5.1 and Calibre 5.26