I think what is really needed is another switch (when all else fails, add another switch!). Fundamentally, only the application can decide whether errors such as access denied should be catastrophic or not. Based on the behaviour of my Windows backup programs, I would imagine backup programs for example to skip inaccessible files as opposed to aborting. An installer copying files might treat errors reading source directories as catastrophic. Since glob can't tell the difference, it needs a switch, `-skiponerror` or similar. Which would of course require a TIP.