Why was '~' chosen to represent the home directory? | Hacker News Reader

Why was '~' chosen to represent the home directory?

unix.stackexchange.com

62 pointsptwobrussell17 comments

Previous discussion: https://news.ycombinator.com/item?id=5090344 (405 points, 307 days ago, 157 comments)

I would like to see a re-emergence of this keyboard design, with some added modern enhancements like function keys, command/control/option/etc. modifiers, and media keys.

I recently noticed that the Macbooks' Japanese Keyboard Layout is surprisingly similar to these Terminal keyboard layouts. I wonder why this is?

https://discussions.apple.com/servlet/JiveServlet/showImage/...

$ is on 4 and ¥ way off to the right on the Japanese keyboard?

Speaking of the ¥, notice how it's right under the |?

Early Japanese codepages put ¥ where ASCII has the backslash. Even today, on most (if not all) OSes render the \ as ¥ when using the Japanese locale.

Further reading: http://blogs.msdn.com/b/michkap/archive/2005/09/17/469941.as...

Interesting, I think the South Koreans did the same thing.

Installing South Korean games (this was middle school), I've always wondered why the paths were showing up as :

    C:₩Program Files₩GRAVITY₩RO

And trying to type \ in the installation path input box results in ₩

~, Ctrl, @, etc.

The keyboards — the Japanese layout and the ADM-3A — are bit-paired, meaning that the characters on an unshifted and shifted key differ in exactly one bit in the ASCII encoding.

   SP !  "  #  $  %  &  '  (  )  *  +  ,  -  .  /
   0  1  2  3  4  5  6  7  8  9  :  ;  <  =  >  ?
   @  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O
   P  Q  R  S  T  U  V  W  X  Y  Z  [  \  ]  ^  _
   `  a  b  c  d  e  f  g  h  i  j  k  l  m  n  o
   p  q  r  s  t  u  v  w  x  y  z  {  |  }  ~  DEL

Shift toggles bit 4 of the numeric and low punctuation keys (codes < 0x40), and bit 5 of the alphabetic and high punctuation keys. This made terminals easier and cheaper to build, in the days before cheap microprocessors, when encoding was done in discrete logic or, like the Teletype 33, mechanically.

Some programs from that era have keyboard shortcuts that were comfortably done on those ancient keyboards, but are unnatural enough to cause injuries on modern keyboards [1].

[1] http://en.wikipedia.org/wiki/Emacs#Emacs_pinky

In practice I suspect this tends to manifest itself as hassle, as the user remaps their keyboard, rather than damage to the user's hands. At least I hope so.

Somewhat related: Long term Vi use has caused my standard right hand position to shift one key left. I don't even use hjkl that much anymore, but Vim (and probably more than a little nethack) have changed how I touch-type with QWERTY.

I don't have this issue with VI, but I do have that problem with FPS games that use the wasd keys -- I can only use them if I move my left hand to the left one key space. So I end up remapping those control keys one to the right, in games where that is possible.

also known as path dependence, http://en.wikipedia.org/wiki/Path_dependency

also interesting: http://www.catonmat.net/blog/why-vim-uses-hjkl-as-arrow-keys...

I'd be more interested on why the control key was removed from the home row to help out those who where too lazy to use the shift key or macro a simple translit to their workflow: tr 'a-z' 'A-Z'

When the datamining show is over let me know. I'm in need of a well paying position and interested in moving out to california. I can teach shell automation, programming paradigms and productive workflow to eager learners new to the UNIX programming environment, hacking and building their own tools.

Oh! Is this also why, when using git, HEAD~1 and HEAD^1 are equivalent? Or is it coincidence that they're on the same key?

HEAD~1 and HEAD^1 are equivalent, but HEAD~n and HEAD^n aren't.

HEAD~n means "the n-parent of HEAD, always choosing the first parent." So HEAD~3 means the first parent of the first parent of the first parent of HEAD.

HEAD^n means "the nth parent of head". git commits can have multiple parents if they are merges. So HEAD^3 means the third parent of HEAD.

As a result, HEAD~1 means "the first parent of HEAD" and HEAD^1 means "the first parent of HEAD", but the 1 means two completely different things.

The gitrevisions manpage is pretty mindblowing: https://www.kernel.org/pub/software/scm/git/docs/gitrevision...

Git was released in 2005, so while it's probably not a coincidence it most likely has nothing to do with a keyboard from the 70s.

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