added example (currently with sideeffects)

examples/helloshell.lua

@@ -0,0 +1,19 @@
+-- o/third_party/lua/lua.com helloshell.lua | sort | uniq
+-- output:
+--   124060
+--   130754
+--   2924
+--   2943
+--   2944
+
+function capture(cmd)
+  local f = io.popen(cmd,'r')
+  local s = f:read("*a")
+  f:close()
+  return s
+end
+
+for i=1, 100 do
+  local stdout = capture('ls -laR / 2>&1')
+  print(stdout:len())
+end