1,001 reputation
46
bio website cheshireeng.com
location Monrovia, CA
age 50
visits member for 3 years, 7 months
seen Sep 26 at 21:22

Engineer, Magician, Jack of all Trades


Jun
9
awarded  Commentator
May
22
comment Can I achieve functionality similar to interrupts in Linux userspace?
When the kernel wakes a task for IO completion, I believe it will get some priority boost. It will not provide a hard guarantee for the worst-case latency, however, since there are lots of reasons that just making the process runable will still leave lots of work to do before the process can actually run. But it is probably the best latency that you can get from an unmodified kernel.
May
22
answered Can I achieve functionality similar to interrupts in Linux userspace?
May
22
comment Corruption-proof SD card filesystem for embedded Linux?
@SF. sure. But for applications where UI is limited (think appliance with no UI at all) then having something to guarantee a clean shutdown after just throwing a switch would be very handy. And in any real application, the RPi or whatever won't be the majority of the cost. For my current application, a Gumstix (OMAP4 based) module will be on battery power and there is no UI at all. Weight is a real issue, so I'm likely to be told that I can't have hardware at all and may need to go down the RAM disk route to make it safe.
May
22
comment Corruption-proof SD card filesystem for embedded Linux?
I'd love to see someone design the module that provides just enough power for a clean shutdown, along with the needed system support to heed the warning and actually shut down. It seems like it ought to be a sensible companion to the Pi, BeagleBone, and other tiny Linux machines, but it doesn't seem to exist as a product marked to users of those machines.
Mar
18
awarded  Yearling
Feb
11
comment What is the point of the `cd` external command?
+1 for the observation about side effects and error messages. It is not always well explained to new users that a lot of clever idioms in Unix come from careful use of side effects. And the man pages themselves have never been good at describing the bigger picture.
Nov
11
comment How Wine is not an emulator?
WINE is also a slightly stretched backronym, a kind of humor that appeals to the personality required to create WINE in the first place.
Oct
7
comment Why is Linux's filesystem designed as a single directory tree?
@BruceEdiger I'm not going to try to argue that DOS was right. Just pointing out that there is context for why Windows is the way it is, and that it wasn't just something that MS pulled out of a hat.
Oct
7
comment Why is Linux's filesystem designed as a single directory tree?
Minor nitpick: the drive letters in Windows default to ascending alphabetical order, but they can be and often are renamed.
Oct
7
comment Why is Linux's filesystem designed as a single directory tree?
And that (rhetorical) question does have an answer: tradition. Just a different tradition than Unix came from. Windows gets this from DOS, which gets it from CP/M-80, which followed a common pattern of many minicomputer and mainframe operating systems. The drive names just got shortened from DISK0: or SY: to A:.
Mar
18
awarded  Yearling
Nov
30
comment Why there are multiple shells in a Unix like system?
Even COMMAND.COM in DOS was replaceable. However, you often got a very brittle system due to the assumptions of other applications (and other users). As a result, there are few successful alternatives to CMD.EXE. One is PowerShell, which has the inertia of Microsoft backing it. Another example is, strangely enough, bash due to decent support from the Cygwin community, not to mention the MinGW folks. As for Window Managers, Windows has only had one at a time, but there have been several over time as the Windows environment itself evolved.
Mar
18
awarded  Yearling
Feb
8
awarded  Good Answer
Jul
21
comment Shell and applications
You will notice that /bin/[ exists, and is a hard link to /bin/test on most (all?) *nix boxes. It wasn't a builtin to the classic Bourne shell. There are also confusing animals such as busybox that implement most of core commands and a shell, deciding which they are at run time by inspecting the name used to invoke them.
Jul
21
comment Shell and applications
Note that many builtins are also available as external commands, probably in /usr/bin or /bin. This is largely for historical reasons; the classic Bourne shell had far fewer builtins than bash does.
Apr
28
awarded  Editor
Apr
28
revised How to unfreeze after accidentally pressing Ctrl-S in a terminal?
stupid typo
Apr
28
comment How to unfreeze after accidentally pressing Ctrl-S in a terminal?
I used to wonder why DEL had the code 127 rather than being grouped with the other control characters, until I first played with some paper tape and an ASR33. Once I realized that it had the effect of punching all the holes, which meant it could be overstruck on any previously punched character to delete it, it made sense.