Mike Meredith

Messing With Rofi: Inserting Unicode

 Computing, Linux, Working Notes  No Responses »
Feb 292020
 

I used to be able to remember all of the keyboard short-cuts I’d set up to insert ‘fun’ (or useful) Unicode characters … but my memory isn’t quite what it used to be, and I happened to catch a video that mentioned a menu to insert Unicode characters.

So I set out to create my own …

#!/bin/zsh
#
# Run a menu of Unicode characters to put into the clipboard

read -r -d '' menu << END
Þ       Thorn (Sym-t)
Þ	Capital thorn (Sym-T)
✓	Tick (Sym-y)
✔       Alternate tick (Sym-Y)
π	pi (Sym-p)
Π       PI (Sym-P)
★       Star
🖕      Finger
END

selectedchar=$(echo $menu |\
  rofi -dmenu -l 20 -fn misc-24 -p "Unicode inserter" |\
  awk '{print $1}')
if [ -z "$selectedchar" ]
then
  notify-send "Unicode Inserter" "Cancelled"
else
  printf "%s" $selectedchar | xclip -selection clipboard
  notify-send "Unicode Inserter" \
    "Character $selectedchar now in clipboard"
fi

This script :-

  1. Creates a variable with a whole pile of text inside it. The original script contains a lot longer list, but including it would be a) boring and b) give too much away. As it stands, the format of each line is pretty much anything you want as long as the first character is the Unicode character followed by whitespace.
  2. Runs rofi with the variable as input and selects the first field of the response.
  3. Guards against the empty selection (when the menu was cancelled) for neatness mostly.
  4. Prints the selected character (without a newline) into xclip so it can be pasted in. I did try using xdotool to type it directly into the active window, but this didn’t always work so well (i.e. xdotool couldn’t “type” some of the more esoteric characters).
  5. And uses notify-send to alert the dumb user (me!) that something has happened.

Lastly, to make this useful, I added an entry to my sxhkd configuration :-

super + F11
  /site/scripts/m-unicode-insert

Virtual Cores Are Not Physical Cores

 Computing  No Responses »
Feb 242020
 

Every so often, I tune into a video on some form of virtualisation which perpetuates the myth that ‘virtual cores’ that you allocate to a virtual machine are equivalent to the physical cores that the host has. In other words if you create a virtual machine with two cores, that is two cores that the rest of the host cannot use.

Preposterious.

Conceptually at least, a core is a queue runner that takes a task on a queue, runs that task for a while, and then sticks that task back on the queue. Except for specialised workloads, those cores are very often (even mostly) idle.

To the host machine, tasks scheduled to run on a virtual core are just tasks to be performed waiting in the queue; ignoring practicality, there is no reason why there should not be more virtual cores in a virtual machine than there are in the host machine.

If you take a look at the configuration of my virtual Windows machine in VirtualBox :-

You see :-

  1. I’ve allocated 8 virtual cores to this machine. I rarely use this machine (although it is usually running), but it does not take much resources to run idle cores.
  2. VirtualBox arbitrarily limits the number of cores I can allocate to the virtual machine to the number of threads my processor has; it also has a warning at the number of cores my processor has but doesn’t stop me allocating virtual cores in the “red” zone.

Qemu on the other hand has no such qualms about launching a virtual machine with 64 cores – well in excess of what my physical processor has.

Of course you have to be sensible, but creating a virtual machine with 4 cores does not make four cores unavailable to your host machine. If a virtual machine is idle, it won’t be running much (no machine is ever completely idle) on your real cores.

On The Banality of Pascal’s Wager

 Religion  No Responses »
Jan 232020
 

For those who are tuning in a bit late, Blaise Pascal came up with the believer’s so-called ‘rational’ argument for believing (or trying to believe) in a god. The argument goes something like :-

  • God is, or God is not. Reason cannot decide between the two alternatives
  • A Game is being played… where heads or tails will turn up
  • You must wager (it is not optional)
  • Let us weigh the gain and the loss in wagering that God is. Let us estimate these two chances. If you gain, you gain all; if you lose, you lose nothing
  • Wager, then, without hesitation that He is. (…) There is here an infinity of an infinitely happy life to gain, a chance of gain against a finite number of chances of loss, and what you stake is finite. And so our proposition is of infinite force when there is the finite to stake in a game where there are equal risks of gain and of loss, and the infinite to gain.
  • But some cannot believe. They should then ‘at least learn your inability to believe…’ and ‘Endeavour then to convince’ themselves.

Sounds reasonable doesn’t it? Of course it does – Pascal has used logic here even though he is coming to an irrational conclusion; the key is logic.

However there is only one small area where Pascal’s wager makes any kind of sense – if believers burn atheists at the stake (which did happen during Pascal’s lifetime) then it makes perfect sense to pretend to believe to protect oneself.

However it does make two rather large assumptions :-

  1. That this god isn’t able to determine the difference between believing and pretending to believe. Which kind of invalidates the notion of an omniscient god.
  2. Which god? Given the childish jealousy that most gods exhibit, pick the wrong one and you’re in just a bad a position as someone who doesn’t pick at all.

And the very first statement – that reason cannot determine whether god exists or not, is completely wrong. Reason requires evidence for the existence of something, and the best evidence for the existence of god is the belief of the believers which isn’t evidence at all.

Light’s Shadow
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