TUHS

tuhs@tuhs.org

28 participants
6556 discussions

Re: [TUHS] Less -- was Termcap vs terminfo

by Doug McIlroy

> when you - say - run less to display a file, it switches to a dedicated > region in the terminal memory buffer while printing its output, then > restores the buffer to back where you were to begin with when you exit > the pager Sorry for veering away from Unix history, but this pushed one of the hottest of my buttons. Less is the epitome of modern Unix decadence. Besides the maddening behavior described above, why, when all screens have a scroll bar, should a pager do its own scrolling? But for a quantitative measure of decadence, try less --help | wc. It takes excess to a level not dreamed of in Pike's classic critique, "cat -v considered harmful". Doug

10 years, 7 months

SVN of CSRG Releases

by Warren Toomey

Hi all, I came across this last week: http://svnweb.freebsd.org/ It's a Subversion VCS of all the CSRG releases. I'm not sure if it has been mentioned here before. Cheers, Warren

10 years, 7 months

Re: [TUHS] Termcap vs terminfo

by David Barto

<much discussion about quadratic search removed> All I remember (and still support to this day) is that I’ve got a TERMCAP=‘string’ in my login scripts to set termcap to the specific terminal I’m logging in with. Long ago this made things much faster. Today I think that it is just a holdover that I’m not changing due to inertia, rather than any real need for it. David — David Barto david(a)kdbarto.org

10 years, 7 months

Fixed Unix v5 bug!

by Mark Longridge

> Noel Chiappa > The change is pretty minor: in this piece of code: > > case reboot: > termall(); > execl(init, minus, 0); > reset(); > > just change the execl() line to say: > > execl(init, init, 0); I patched init in v5 and now ps shows /etc/init as expected, even after going from multi to single to multi mode. Looks like init.c was the same in v5 and v6.

10 years, 7 months

Early Unix file system checks

by Mark Longridge

> Noel Chiappa: > Just out of curiousity, why don't you set the SR before you boot the machine? > That way it'll come up single user, and you can icheck/dcheck before you go > to multi-user mode. I prefer doing it that way, there's as little as possible > going on, in case the disk is slightly 'confused', so less chance any bit-rot > will spread... I actually do file system checks on v5 as it's the early unix I use the most: check -l /dev/rk0 check -u /dev/rk0 same for rk1, rk2. The v5 manual entry for check references the 'restor' command, although the man page for that is missing. Your idea of starting up in single user mode is a good one although I'm not sure if it's necessary to check the file system on each boot up. I've been running this disk image of v5 for about two years and no blow-ups as yet. I also keep various snapshots of v5, v6 and v7 disk images for safety reasons. And there are text files of all the source code changes I've made, so if disaster strikes I can redo it all. Mark

10 years, 7 months

Re: [TUHS] single user mode in v5 & v6

by jnc＠mercury.lcs.mit.edu

> From: Clem Cole > ps "knew" about some kernel data structures and had to compiled with > the same sources that your kernel used if you want all the command > field in particular to look reasonable. Not just the command field! The real problem was that all the parameters (e.g. NPROC) were not stored in the kernel anywhere, so if you wanted to have one copy of the 'ps' binary which would work on two different machines (but which were running the same version of the kernel)... rotsa ruck. I have hacked my V6 to include lines like: int ninode NINODE; int nfile NFILE; int nproc NPROC; etc so 'ps' can just read those variables to find the table sizes in the running kernel. (Obviously if you modify a table format, then you're SOL.) > From: Ronald Natalie > The user structure of the currently running process is the only one > that is guaranteed to be in memory ... Any processes that were swapped > you could read the user structure so things that were stored there were > often unavailable (particularly the command name). Well, 'ps' (even the V6 stock version) was actually prepared to poke around on the swap device to look at the images of swapped-out processes. And the command name didn't come from the U area (it wasn't saved there in stock V6), 'ps' actually had to look on the top of the user stack (which is why it wasn't guaranteed to be accurate - the user process could smash that). > From: Clem cole > IIRC we had a table of sleep addresses so that ps could print the > actual thing you were waiting for not just an address. I've hacked my copy of 'ps' to grovel around in the system's symbol table, and print 'wchan' symbolically. E.g. here's some of the output of 'ps' on my system: TTY F S UID PID PPID PRI NIC CPU TIM ADDR SZ TXT WCHAN COMMAND ?: SL S 0 0 0-100 0 -1 127 1676 16 runout <swapper> ?: L W 0 1 0 40 0 0 127 1774 43 0 proc+26 /etc/init ?: L W 0 11 1 90 0 0 127 2405 37 tout /etc/update 8: L W 0 12 1 10 0 0 127 2772 72 2 kl11 - a: L W 0 13 1 40 0 0 127 3122 72 2 proc+102 - a: L R 0 22 13 100 0 10 0 3422 138 3 ps axl b: L W 0 14 1 10 0 0 127 2120 41 1 dz11+40 - 4 It's pretty easy to interpret this to see what each process is waiting for. Noel

10 years, 7 months

Re: [TUHS] single user mode in v5 & v6

by jnc＠mercury.lcs.mit.edu

> From: Noel Chiappa > For some reason, the code for /etc/init .. bashes the command line so > it just has '-' in it, so it looks just like a shell. BTW, that may be accidental, not a deliberate choice - e.g. someone copied another line of code which exec'd a shell, and didn't change the second arg. > I fixed my copy so it says "/etc/init", or something like that. ... I > can upload the 'fixed' code tomorrow. The change is pretty minor: in this piece of code: case reboot: termall(); execl(init, minus, 0); reset(); just change the execl() line to say: execl(init, init, 0); >> I'm not sure if unix of the v6 or v5 era was designed to go from multi >> user to single user mode and then back again. > I seem to recall there's some issue, something like in some cases > there's an extra shell left running attached to the console So the bug is that in going from single-user to multi-user, by using "kill -1 1" in single-user with the switch register set for multi-user, it doesn't kill the running single-user shell on the console. The workaround to that bug which I use is to set the CSWR and then ^D the running shell. In general, the code in init.c isn't quite as clean/clear as would be optimal (which is part of why I haven't tried to fix the above bug), but _in general_ it does support going back and forth. > From: Ronald Natalie > our init checked the switch register to determine whether to bring up > single or multiuser I think that's standard from Bell, actually. > I believe our system shutdown if you kill -1-1 (HUP to init). The 'stock' behaviour is that when that happens, it checks the switch register, and there are three options (the code is a little hard to follow, but I'm pretty sure this is right): - if it's set for single-user, it shuts down all the other children, and brings up a console shell; when done, it does the next - if it's set for 'reboot', it just shuts down all children, and restarts the init process (presumably so one can switch to a new version of the init without restarting the whole machine); - if it's not set for either, it re-reads /etc/ttys, and for any lines which have switched state in that file, it starts/kills the process listening to that line (this allows one to add/drop lines dynamically). > From: Clem Cole > it's probably worth digging up the v6 version of fsck. That's on that MIT V6 tape, too. Speaking of which, time to write the code to grok the tape... Noel

10 years, 7 months

Re: [TUHS] single user mode in v5 & v6

by jnc＠mercury.lcs.mit.edu

> From: Mark Longridge <cubexyz(a)gmail.com> > I've finally managed to get Unix v5 and v6 to go into single user mode > while running under simh. > ... > dep system sr 173030 (simh command) Just out of curiousity, why don't you set the SR before you boot the machine? That way it'll come up single user, and you can icheck/dcheck before you go to multi-user mode. I prefer doing it that way, there's as little as possible going on, in case the disk is slightly 'confused', so less chance any bit-rot will spread... > Now I'm in muti user mode .. but then if I do a "ps -alx" I get: > > TTY F S UID PID PRI ADDR SZ WCHAN COMMAND > ?: 3 S 0 0-100 1227 2 5676 ???? > ?: 1 W 0 1 40 1324 6 5740 - > The ps command doesn't show the /etc/init process explicitly, although > I'm pretty sure it is running. No, it's there: the second line (PID 1). For some reason, the code for /etc/init (in V6 at least, I don't know anything about V5) bashes the command line so it just has '-' in it, so it looks just like a shell. I fixed my copy so it says "/etc/init", or something like that. The machine my source is on is powered down at the moment; if you want, I can upload the 'fixed' code tomorrow. > I'm not sure if unix of the v6 or v5 era was designed to go from multi > user to single user mode and then back again. I seem to recall there's some issue, something like in some cases there's an extra shell left running attached to the console, but I don't recall the details (too lazy to look for the note I made about the bug; I can look it up if you really want to know). > Would it be safer to just go to single user and then shut it down? I don't usually bother; I just log out all the shells except the one on the console, so the machine is basically idle; then do a 'sync', and shortly after than completes, I just halt the machine. Noel

10 years, 7 months

Re: [TUHS] COHERENT sources released under 3-clause BSD license.

by Rico Pajarola

adding the list back On Tue, Jan 6, 2015 at 10:42 AM, Michael Kerpan <mjkerpan(a)kerpan.com> wrote: > This is a cool development. Does this code build into a working version of > Coherent or is this mainly useful to study? Either way, it should be > interesting to look at the code for a clone specifically aimed at low-end > hardware. > > Mike >

10 years, 7 months

single user mode in v5 & v6

by Mark Longridge

Ok, I've finally managed to get Unix v5 and v6 to go into single user mode while running under simh. I boot up unix as normal, that is to say in multi-user mode. Then a ctrl-e and dep system sr 173030 (simh command) then c to continue execution of the operating system and finally "kill -1 1". This gets me from multi user mode to single user mode. I can also go back to multi user mode with: ctrl-e and dep system sr 000000 then once again c to continue execution of the operating system and "kill -1 1". Now I'm in muti user mode, and I can telnet in as another user so it seems to be working but then if I do a "ps -alx" I get: TTY F S UID PID PRI ADDR SZ WCHAN COMMAND ?: 3 S 0 0-100 1227 2 5676 ???? ?: 1 W 0 1 40 1324 6 5740 - 8: 1 W 0 51 40 2456 19 5766 - ?: 1 W 0 55 10 1377 6 42066 - ?: 1 W 0 5 90 1734 5 5440 /etc/update ?: 1 W 0 32 10 2001 6 42126 - ?: 1 W 0 33 10 2054 6 42166 - ?: 1 W 0 34 10 2127 6 42226 - ?: 1 W 0 35 10 2202 6 42266 - ?: 1 W 0 36 10 2255 6 42326 - ?: 1 W 0 37 10 2330 6 42366 - ?: 1 W 0 38 10 2403 6 42426 - 8: 1 R 0 59 104 1472 17 ps alx The ps command doesn't show the /etc/init process explicitly, although I'm pretty sure it is running. I'm not sure if unix of the v6 or v5 era was designed to go from multi user to single user mode and then back again. Would it be safer to just go to single user and then shut it down? Mark

10 years, 7 months

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TUHS