qlmanage

QuickLook server tool. More information: https://keith.github.io/xcode-man-pages/qlmanage.1.html.

Display QuickLook for one or multiple files:

qlmanage -p {{path/to/file1 path/to/file2 ...}}

Compute 300px wide PNG thumbnails of all JPEGs in the current directory and put them in a directory:

qlmanage {{*.jpg}} -t -s {{300}} {{path/to/directory}}

Reset QuickLook:

qlmanage -r