bash job server

parallel.bash

# `parallel <cmd...>` works similarly to `<cmd...> &` but limits the
# maximum job count to prevent over-zealous memory consumption when
# batch processing huge numbers of files.
parallel () {
	while [ "$(jobs | wc -l)" -ge $((3 * $(nproc) / 2)) ]
	do
		wait -n
	done
	"$@" &
}

for f in $jpegs
do
	parallel convert $f --resize ...
done