with the command you've used only 'gdk-pixbuf-query-loaders' was run as sudo and the redirection of the output to /usr/lib/x86_64-linux-gnu/... was done as yourself.
Try sudo -i to start a root prompt then run:
gdk-pixbuf-query-loaders > /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/2.10.0/loaders.cache
Then logout as root.
with the command you've used only 'gdk-pixbuf- query-loaders' was run as sudo and the redirection of the output to /usr/lib/ x86_64- linux-gnu/ ... was done as yourself.
Try sudo -i to start a root prompt then run:
gdk-pixbuf- query-loaders > /usr/lib/ x86_64- linux-gnu/ gdk-pixbuf- 2.0/2.10. 0/loaders. cache
Then logout as root.