Cool Mac Gear

Here's a weird one. Twice in the past week, I've had screen lockups in OS X on my iBook. In both cases it happened while I was doing some routine task, the first time I think I was in Nisus Email; the second I was definitely in Eudora -- trying to open a message or clicking on a button when the cursor froze -- just like a screen freeze in the old Mac OS X, only no MacsBug to bail me out without a restart. In the first instance I was running OS 10.2.1; in the second 10.2.3.

I'm talking about complete non-response to pointing device input from either the external mouse, the keyboard, or the built-in trackped. No spinning beachball; no nothing. I tried waiting a while, but that didn't work. The only recourse I could think of was the old three finger salute -- Command > Control > Power Key to force restart the computer. It has since dawned on me that I could also have tried Command > Option > Escape, but I didn't think of it at the time, and I don’t think it would have worked anyway. The iBook wasn;t responding to the keyboard.

Harrumph. I thought this sort of thing wasn’t supposed to happen in OS X, and indeed it never has happened in my experience on my trusty old Pismo PowerBook. However, twice in one week is a LOT higher frequency than I've gotten Finder lockups in OS 9 in recent years.

If anyone else out there has encountered this phenomenon or can shed some light on what's causing it, please let me know.

Deleting Stubborn Files

From Anonymous

Hi Charles,

I haven't had time to read your columns in quite awhile, but checked in today to see that you had a stubborn file that wouldn't go away. This issue can be quite common when a download fails to complete (especially from IE or any of the Mozilla variants), as the file is actually not owned by you until it is completed and decompressed, where required.

Some browser's downlaod managers will allow you to delete the file by clearing the item or using a Control-Click Contextual Menu item, or sometimes it's in the download manager's Get Info pane for that item. Not all browsers will help you here.

The next way, in Finder GUI, around this in 10.2.x is to simply do a 'Get Info' on the errant file; choose the 'Ownership & Permissions' section; click the lock icon and enter your admin password (if required); change ownership to you; move or delete as desired. Somewhat tedious, but it beats a reboot.

A much faster way is to type:

sudo rm

Followed by a 'space' character into the Terminal, then drag the icon of the errant file to the same Terminal Window; Terminal will automagically fill in the correct file path for you; observe the file path briefly to make sure you didn't accidentally drag the wrong (or multiple wrong) files; e.g.:

[Computer Name:~] username% sudo rm
/Users/username/Desktop/bad_download_file_name.something

(the above will appear on one line if your Terminal window is large enough)

Then just press 'Enter' (or 'Return'), enter your admin password, and poof, the file is gone. Keep in mind that it's really, really gone, so use this carefully. This is one of many reasons why a lot of us keep Terminal running at all times, so we don't have to wait for it to launch when we just want a quick window operation like this.

There's also numerous freeware widgets, AppleScripts, and utilities to allow you to drag'n'drop such files, or use a Contextual Menu item to delete (or just move to the Trash to be more safe for less-experienced users).

Also noted you were considering using SwapSwapVM or other utilities (to change your Virtual Memory location; I highly recommend trying it out, as it is only a quick application run and a Restart away from trying out; If you don't like the results, just switch it back. It's really no different than using the old Memory CP in the old Mac OS to switch, except that you have to go download a utility to get started.

I use SwapSwapVM, and have been very happy with its safety features, which are not found in the other utilities, like Xupport, last I checked (support for disks with spaces or special characters in names, code to recover if the disk is renamed or removed, etc.).

HTH

Anon

Hi Anon;

Thanks for the helpful tutorial on stubborn file deletion and the report on SwapSwapVM. I’m using the iBook for production lately, but when I get back on the Pismo I’ll look into moving the swap file.

What say you about the caveat that on a slow disk, you may lose as much speed to longer read head travel as you gain from more breathing space by moving the swap file(s) to another partition?

Charles

More on multiple mice

From Michael Snider

Charles,

You wrote, about OS X's handling of multiple pointing devices "Sorry, but from my perspective it is a flaw. I didn't come up with anything ingenious in OS 9. Multiple pointing devices just worked. Plug and play. Seems to me that must have been intentional."

It's been a long time (10+years) since I've done any programming which required looking at ADB ports, but my admittedly faulty memory tells me that devices on the bus could not be identified--a signal came across from who knows where saying "mouse-up" or "ASCII 40" or whatever, and the forever GetNextEvent loop responded. Mutliple devices worked not because of design but because you couldn't separate them, and it's unlikely that that was designed. It's more likely no one thought there would ever be two mice when ADB was specced, just as no one thought there would be a need for protected memory on the Mac because the expectation was that there would never be more than one app running, or more than one user.

USB isn't perfect, but you can identify a device on the bus. When a device is performing an action on the selected object, in almost all cases it's important to prevent other devices from interrupting that action, and well-programmed drivers will do it that way. When no action is currently being performed on an object, as when the mouse pointer is simply being moved across the screen, it's less important to separate the actions of various devices, but it's nevertheless a bug to conflate them unless the hardware and software is specifically designed for unusual situations like yours. That can be done, but it takes money.

So if it's a bug, why not fix the vestiges of pointing-device-interference in OS X?If many people did use multiple mice, it would happen. But it's so rare--in nearly twenty years of Mac use, some of in companies where hundreds of Macs got used, I've seen it maybe twice when it wasn't a joke--it probably doesn't even get tested, except on notebooks to make sure the system follows the preference setting to ignore the trackpad when a mouse is plugged in.

Best,
Michael

Hi Michael;

I defer to your greater erudition on the topic of programming. However, it makes me pine even more for the old ADB bus.

However, the multi-mouse mode does seem to work fine with USB devices in OS 9, so it’s not an inherent USB issue. This is on the same computers using the same input devices. The variable is OS X, which does not support multiple mice without kludging (on the Pismo I can make it work by keeping the click-lock on in the Wacom Graphire II tablet mouse, but this workaround doesn’t work with the iBook).

I also concede the obvious that only a small minority of users would be inconvenienced by this, although I think that if more folks got used to the extra speed one gets by tandem-mousing, more people would use the technique, even absent any physical disabilities. In any case, there is enough demand for foot mice to keep then in manufacture at very high prices. I just use a regular mouse with a long cord, but in either case, I assume that exclusive use of a single foot mouse is not expected unless one has not the use of their hands.

Also, multiple USB device input is inherent in the overlap between keyboard and mouse functions.

Thanks for the discussion.

Charles

The OS X Odyssey archives may be accessed here:
http://www.applelinks.com/news/odyssey/

CM

Charles W. Moore