[[ -f /proc/mounts ]] || {
  echo "mkofs: only supported on linux" >&2
  return 2
}
local o
if [[ -d o ]]; then
  o=$(pwd -P)/o
else
  echo "mkofs: o/ not found" >&2
  echo "suggested preparation:" >&2
  echo "    mkdir -m 555 o" >&2
  return 1
fi
cut -d' ' -f2 /proc/mounts | while read -r line; do
  if [[ "$o" = "$line" ]]; then
    echo "mkofs: $o already mounted" >&2
    return 0
  fi
done
( set -x
  sudo mount -t tmpfs -o size=10G,noatime,nodiratime /dev/shm "$o"
)
# vim:ft=zsh