#! /bin/sh
# undot_paths : lines path |> lines path
# Remove all dots (. and ..) from input paths.
set -euf

sed '
  :0
  s://\+:/:g
  s:/\.\(/\|$\):\1:g
  s:/[^/]\+/\.\.\(/\|$\):\1:g
  s:^/\(\.\./\)\+:/:
  t0
  s:^$:/:
'