Re: [TUHS] pre-more pager?

Random832: ... and "p" (which is very minimalistic, despite using a few V8-specific library features, but V8 isn't in the web-accessible source archive) from Version 8 research unix. ==== p actually originated outside Bell Labs. I think it was written in the late 1970s at the University of Toronto. I first saw it at Caltech, on the UNIX systems in the High Energy Physics group that I ran for four years. The first few of those systems were set up by Rob Pike, who was at Caltech working on his masters degree (in astrophysics, I think); p was there because Rob brought it. For those who don't know it, p has quite an elegant design. Its default page size is 22 lines, which nicely fit the world of its time: allowed a couple of lines of context between pages on a 24-line CRT; evenly divided the 66-line pages (still!) output by nroff and pr. It uttered no prompt and required neither raw nor cbreak nor even no-echo mode: it printed the final line of each page sans newline; to continue, you typed return, which was echoed, completing that line before the next was printed. It buffered text internally to allow backing up a few pages, so it was possible to back up even when input didn't come from a file (something I'm not sure the more of the time could do). Internally the buffering was done with a standalone library that could have been used in other programs, though I don't know whether it ever was. p also led me to an enlightening programming story. One day I was looking over the code, trying to understand just how the buffering worked; part of it made no sense to me. To figure it out, I decided to write my own simple, straightforward version with the same interface; test and debug it carefully; then lay printouts of the two implementations side-by-side, and walk through some test cases. This revealed that the clever code I couldn't make out in the original was actually buggy: it scrambled data (I forget the details) when read returned less than a full buffer. p (my version) is one of the several programs I bring along to every new UNIX-derivative environment. I use it daily. I have also recently noticed a new bug: on OpenBSD, it sometimes scrambles the last few lines of a file. I have figured out that that has something to do with whether fclose (my version uses stdio) is called explicitly or by exit(3), but I don't know yet whether it's the library's fault or my own. Even the simplest programs have things to teach us. Norman Wilson Toronto ON