Translation into plain:
\vsize=30cm
1
\saveimageresource{example-image.pdf}\hbox{\useimageresource\lastsavedimageresourceindex}
2
\saveimageresource{example-image-a.pdf}\hbox{\useimageresource\lastsavedimageresourceindex}
3
\saveimageresource{example-image-b.pdf}\hbox{\useimageresource\lastsavedimageresourceindex}
\directlua{
os.execute("lsof | grep latex | grep example")
}
\bye
untested as I don't have lsof here, it seems.
