[htp]

Took some time to figure out how to type these on a Mac:

1. Go to System Preferences => Keyboard => Input Sources

2. Add Unicode Hex Input as an input source

3. Switch to Unicode Hex Input (assuming you still have the default keyboard shortcuts set up, press Command+Shift+Space)

4. Hold Option and type 001f to get the unit separator

5. Hold Option and type 001e to get the record separator

6. (Hold Option and type a character's code as a 4-digit hex number to get that character)

Sadly, this doesn't seem to work everywhere throughout the OS- I can get control characters to show up in TextMate, but not in Terminal.

[quesera]

In Terminal, they are:

  FS: Control-\ 0x1c (field sep)
  GS: Control-] 0x1d (group sep)
  RS: Control-^ 0x1e (record sep)
  US: Control-_ 0x1f (unit sep)

(These control key equivalents have always been the canonical keystrokes to generate the codes)

But they have to be preceded by a Control-V (like in vi) to be treated as input characters. Control-V is the SYN code (synchronous idle), but has no special meaning in an interactive context, which is presumably why it was chosen.

The full set of control codes (0x00 - 0x1f) and their historical meanings are why Apple added the open/closed Apple keys, eventually the Command key. They wanted a set of keystrokes that were unambiguously distinct from the data stream.

Control-S, e.g., will pause text output in the Terminal (also xterm, etc). This was super useful in the days before scrollback. :) Control-Q to resume (actually flush all the buffered output).

Overloading Control sequences was an unforgivable sin committed by Microsoft.

...if I remember the history correctly, Apple decided that having both open/closed Apple keys was confusing, and having the Apple logo on the keyboard was tacky, so they renamed the key for the Mac, and Susan Kare selected a new glyph, which is a Scandinavian "point of interest" wayfinding symbol.

...as a further aside, Control-N and Control-O are the cause of the bizarre graphical glyphs you sometimes see if you do something silly like cat a binary file. Control-N initiates the character set switch, and Control-O restores it. This can be used to fix your Terminal when things go awry. Most people just close the window, but I hate losing history. :)

0x20 - 0x74, unshifted:

   !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~

0x20 - 0x74, shifted:

   !"#$%&'()*→←↑↓/▮123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_◆▒bcde°±▒☃┘┐┌└┼⎺⎻─⎼⎽├┤┴┬│≤≥π≠£·

...works in Firefox. YMMV.

Terminal-charset-quickfix: at shell, type "echo ^O". To get the literal ^O, use Control-V then Control-O.

[graywh]

Most terminals will let you use ctrl-6 for ctrl-^ and ctrl-7 (and sometimes ctrl-/) for ctrl-_.