[TUHS] Where did the "~" come from

Mary Ann Horton mah at mhorton.net
Fri Nov 20 03:22:18 AEST 2020

I first saw ~ as part of csh. Bill had an adm3a at home (which is why 
HJKL in vi) but there was a variety of terminals at Berkeley. I assumed 
~ was Bill's idea.

     Mary Ann

On 11/18/20 2:25 PM, Clem Cole wrote:
> A couple of my friends from UC Berkeley were musing on another email 
> thread.   The question from one of them came up: /"I'm teaching the 
> undergrad OS course this semester  ... Mention where ~ comes."/
> This comment begets a discussion among the 4 of us at where it showed 
> up in the UNIX heritage and it if was taken from somewhere else.
> Using the tilde character as a short cut for $HOME was purely a 
> userspace convention and not part of the nami() kernel routine when it 
> came into being.  We know that it was supported by Mike Lesk in UUCP 
> and by Bill Joy in cshell.  The former was first widely released as 
> part of Seventh Edition but was working on V6 before that inside of 
> BTL.  Joy's cshell came out as part of 2BSD (which was V7 based), but 
> he had released "ashell" before that and included it in the original 
> BSD (/a.k.a./ 1BSD) which was for V6 [what I don't remember is if it 
> supported the convention and I can not easily un-ar(1) the 
> cont.a files in the 1BSD tar image in Warren's archives.
> In our exchange, someone observed suggested that Joy might have picked 
> it up because the HOME key was part of the tilde key on the ADM3A, 
> which were popular at UCB [/i.e./ the reason hjkl are the movement 
> keys on vi is the were embossed on the top of those keys on the 
> ADM3A].  It also was noted that the ASR-33 lacks a ~ key on its 
> keyboard.  But Lesk definitely needed something to represent a remote 
> user's home directory because each system was different, so he was 
> forced to use something.
> It was also noted that there was plenty of cross-pollination going on 
> as students and researchers moved from site to site, so it could have 
> been BTL to UCB, vice-versa, or some other path altogether.
> So two questions for this august body are:
>  1. Where did the ~ as $HOME convention come to UNIX?
>  2. Did UNIX create the idiom, or was there an earlier system such as
>     CTSS, TENEX, ITS, MTS, TSS, or the like supported it?
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