Thunar

Useful User Actions:

Resizing images also see ImageMagick

echo %F | awk 'BEGIN { RS = " " }; {print $0}' | xargs -L1 mogrify -resize 50%
echo %F | awk 'BEGIN { RS = " " }; {print $0}' | xargs -L1 mogrify -resize 1000x1000\>

(on Image files, pattern *)

Merge pdfs (pdftk package needed)

pdftk %F cat output merge.pdf

(on filetype pdf)