The timeline you're presenting matches what I recall, also. Nice!
That tidbit about .S vs .a is a lovely detail. "A Research Unix Reader" has other cultural details called out that're similar - https://doc.cat-v.org/unix/unix-reader/A.Research.Unix.Reade.... Two of my favourites are the idea that originally a shell script couldn't be part of a pipeline ("programs that were likely to read from shell scripts, especially sh and ed, were made to read their input one character at a time. It was impossible to pipe into a shell script because the standard input was already dedicated to the script. For the same reason a program in a shell script could not take input from a terminal except when given the terminal’s real name.") and this note from the man page for sort v1:
A bug note in join(1) declares, ‘‘The [field-specification] conventions of join, sort, comm, uniq, look and awk(1) are wildly incongruous.’’ Although these programs are often used together, they remain, like American weights and measures, sturdily eccentric.
I remember thinking that commands were weirdly unsimilar as I was first learning them; it took this many years for me to see one of the early authors wrote an oopsie about them :)
A correction. I can find no evidence of a Unix v2 at Berkeley, it looks like it was v4. (I was told long ago by someone who was at Berkeley then that they had had v2, but there is no evidence of this in the usual sources of information.)
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The timeline you're presenting matches what I recall, also. Nice!
That tidbit about .S vs .a is a lovely detail. "A Research Unix Reader" has other cultural details called out that're similar - https://doc.cat-v.org/unix/unix-reader/A.Research.Unix.Reade.... Two of my favourites are the idea that originally a shell script couldn't be part of a pipeline ("programs that were likely to read from shell scripts, especially sh and ed, were made to read their input one character at a time. It was impossible to pipe into a shell script because the standard input was already dedicated to the script. For the same reason a program in a shell script could not take input from a terminal except when given the terminal’s real name.") and this note from the man page for sort v1:
I remember thinking that commands were weirdly unsimilar as I was first learning them; it took this many years for me to see one of the early authors wrote an oopsie about them :)
A correction. I can find no evidence of a Unix v2 at Berkeley, it looks like it was v4. (I was told long ago by someone who was at Berkeley then that they had had v2, but there is no evidence of this in the usual sources of information.)