HDTenEightyP/NetNews huggingface dataset:
Newsgroups: comp.unix.wizards



If a process does not wait for it's child, then the OS has to hold
the child in defunct state on it's exit, since the parent can request
the exit status later thro' a wait. But if the parent is not
interested in the child's exit status, it can set the SIGCHLD to
SIG_IGN. This will let the kernel know that the parent will not do
a wait on child and prompt it to let an exiting child die peacefully.

Subbu 

HP Cupertino
From: Unix-Wizards@BRL.MIL
Newsgroups: comp.unix.wizards
Subject: >To:
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Newsgroups: comp.unix.wizards
From: bzs@world.std.com (Barry Shein)
Subject: Re: /dev
Organization: The World
Date: Mon, 21 Dec 1992 06:28:10 GMT


From: cq377@cleveland.Freenet.Edu (David C. Williss)
>  2.  How do I print to a remote printer.  I suppose I could fork
>      and exec lpr.  Is that the reccomended method?  

This is what you want to do for both local and remote printers, see
popen(3). The rest of the message is plausible, but mostly an attempt
to impose your former culture on Unix and fraught with peril and
unnecessary complexity as you seemed to sense.

-- 
        -Barry Shein

Software Tool & Die    | bzs@world.std.com          | uunet!world!bzs
Purveyors to the Trade | Voice: 617-739-0202        | Login: 617-739-WRLD
Newsgroups: comp.unix.wizards,comp.unix.programmer,comp.unix.questions
From: bharat@sj.ate.slb.com (Bharat Venkatasubramanian)
Subject: Portability issues in using a memory dump
Originator: bharat@surya
Organization: Schlumberger Technologies, San Jose, CA
Date: Thu, 17 Dec 92 22:24:02 GMT


Folks!

I have a wierd problem.  I would like to dump the contents of a chunk of 
contiguous memory locations.   The contents represent some complex graph
structure which once built is constant over different invocations of the 
program.

Instead of traversing the graph and dumping its contents, I would like to
dump the contents of this contiguous memory.  Subsequent invocations of 
this program could then use mmap() system call to map the information in 
this file to the address used when the file was first created.  This would
also preserve the pointer addresses since I am using the same address
space that was used during the creation of this memory dump.  The program
has static behavior until the creation of this graph and so on the same
machine I will definitely be able to guarantee the availability of that
address space.  One of my concerns is will the address space be different
on different Operating Systems??

If any of you folks have tried something like this before, I would appreciate
it if you could share the problems/pitfalls with this solution.

Please email any suggestions to bharat@sj.ate.slb.com

Thanks in advance.

Bharat
Newsgroups: comp.unix.wizards
From: bwendt@nyx.cs.du.edu (Brian Wendt)
Subject: Re: O Wizards, is there vi w/out shell?
Organization: University of Denver, Dept. of Math & Comp. Sci.
Date: Mon, 14 Dec 92 15:33:31 GMT

  I have had problems recently along the same lines:

  There is a public access site in Peoria called Heartland FreeNet.  It
is used exclusivley for email and local newsgroups.  Access is through
menus only, no shell accounts exist.  Denying access to a shell is
basically the only security that exists on the machine - they don't
even bother to set file permissions properly.  The machine is run
by an employee of the Heartland FreeNet Board who is neither UNIX-literate
nor a programmer.

  Recently, I made the mistake of mentioning to the FreeNet administrator
that it was possible to obtain shell access to vi.  I say this was a
mistake because they reacted by simply deleting the vi editor from the
system.

  As I mentioned earlier, this system is used exclusivley for activities
that absolutley require an editor.  So, can anyone give simple, clear
directions that a non-programmer can follow to provide a vi editor
that won't allow shell escapes?  There is no possibility whatsoever
of the HFN adminstrator allowing me or anyone else outside their
organization access to the machine to fix this problem.

Brian Wendt
bwendt@nyx.cs.du.edu
CA2084@siucvmb.siu.edu
Newsgroups: comp.unix.wizards
From: fdm@WLV.IIPO.GTEGSC.COM (Frank D. Malczewski)
Subject: Terminating idle users
Organization: GTE Government Systems
Date: Fri, 18 Dec 92 21:13:19 GMT



I'm wondering whether there is a general approach to determine when a particular
user has been idle for x minutes (no keyboard, mouse, screen i/o), given a
unix system, running X/Motif.  Basically when the user has not done anything
for a period of time, how can one detect this condition?  

Portability is an issue here, but a machine-specific approach would at least
provide a starting point...  (I realize this is likely a pretty tall order,
given that no kernel mods are possible for doing this.)
-- 

Frank Malczewski		(fdm@wlv.iipo.gtegsc.com)
Newsgroups: comp.unix.wizards
From: crf@inmet.camb (Carl Fosler)
Subject: help with tape IO
Organization: Intermetrics, Inc.
X-Newsreader: TIN [version 1.1 PL6]
Date: Sat, 12 Dec 1992 01:24:14 GMT

	I need help interfacing with a tape drive.  The problem is that
after I written a file to tape, I need to write a number of
End-of-tape marks, after which, I have to backup over the tape marks
so we are ready to write the next file (if needed).

	The problem is that I am tring to do this on VAX running 
Unix System V (not BSD or Ultrix).  The tape drive is a TU81.  The tape 
driver does not support MTIOC calls.  I would also like to make it general 
enought so that it should work with any tape drive on a VAX system.

Carl Fosler
Intermetrics, Inc 
McLean, VA   (703) 827-2606
crf@fanny.wash.inmet.com
Newsgroups: comp.unix.wizards,alt.folklore.computers
From: peter@NeoSoft.com (Peter da Silva)
Subject: Re: So You Want To Be A Wizard? (A modest proposal)
Organization: NeoSoft Communications Services -- (713) 684-5900
Date: Wed, 16 Dec 1992 04:39:49 GMT

In article <1992Dec15.194702.24552@blaze.cs.jhu.edu> bogstad@blaze.cs.jhu.edu (Bill Bogstad) writes:
> The other
> advantage of Minix is that although it is a "flakey microkernel"; it is in
> fact a microkernel.  Both OSF and USL seem to be moving their kernels in
> that direction and anyone interested in working with "Unix" systems for the
> long term would gain from this exposure.

Perhaps. I've yet to be convinced that a "Mega-Microkernel" like Minix or
Mach is a significant advance over a "Mini-Macrokernel" like V7 UNIX or
Plan 9. There *are* some nice microkernel operating systems, but the best
way to explore them doesn't involve playing on any variant of UNIX. The
Amiga doesn't have the VM interface, but it is in every real respect a
microkernel design... with seperate execution contexts for each component
of the system software including the device drivers, file systems, and
window system. For a more UNIX-like microkernel try QNX, and (I suspect)
some of the other real-time UNIX workalikes.

No, you don't get to play with the source... but like object oriented
languages, you shouldn't have to. You can do things that would require
kernel hacking in UNIX without getting into the kernel.
-- 
Peter da Silva.  <peter@sugar.neosoft.com>.
 `-_-'   Oletko halannut suttasi tnn?
  'U`    
Tarjoilija, tm ateria el viel.
Newsgroups: comp.unix.wizards
From: synchem@sbcs.sunysb.edu (Synchem proj acct)
Subject: a novice unix internals question
Organization: State University of New York at Stony Brook
Date: Wed, 16 Dec 1992 08:16:48 GMT


Hi,

I'm not a wizard.  But I hope this is a valid question.

In Unix, system calls are executed in the context of the calling process.
In the Leffler 4.3BSD Unix book, it was discussed that the run-time
structure of the kernel is divided into a top and a bottom half.
The top half belongs in each process's address space (may need more
precision).  So  far so good.  My question relates to the bottom half.
The book said that the bottom half "runs on kernel stack in kernel
address space", and is activated to handle mostly hardware interrupts.
It was further mentioned that the bottom half usually runs on a system-wide
interrup stack.  My question is, which process does the bottom half
belong to.  Since hardware handling routines are supposedly short,
and they have their own stack,  but no process state, is it the case that
the interrupt handling routines don't belong to any process? 

Thanks for any help.
From: cthulhu@diku.dk (Stefan Krabbe)
Newsgroups: comp.unix.wizards
Subject: Re: select function
Date: 20 Dec 92 14:10:14 GMT
Organization: Department of Computer Science, U of Copenhagen

tommy@hilbert.att.com (Tom Reingold) writes:

>What do you call versions of UNIX that preceded 4.2 BSD?

Ehh, DOS ? No ?
-- 
                                     ___
  Name:  Stefan Krabbe       .......(o o).......
  Email: cthulhu@diku.dk     ---vvv---U---vvv---
  Institute of Computer Science, University of Copenhagen.
From: 92700217@vax1.dcu.ie (Ciaran Treanor)
Newsgroups: comp.unix.wizards
Subject: How do I invoke a login shell.
Date: 14 Dec 92 14:34:09 GMT

Hi Wizards,
        I know this is probably not the right place to ask this question but
        I need an answer in a hurry. I want to "exec" /bin/csh as a login
        shell from a script file. In the man page for "csh" it says the
        following:

        "If the shell is invoked with a name that starts with '-', as when
        started by login(1) the shell runs as a login shell. In this case,
        after executing commands from the .cshrc file, the shell executes
        commands from the .login file in your home directory."

        How do you invoke /bin/csh with a name that starts with a '-'?
        Do you mess around with argv[0], if so how do you do that in a
        shell script?
        Is there any other of invoking a login /bin/csh?

        I'm working on a Sparc 10 running SunOS 4.1.3.

Thanks in advance and apologies if this is a really stupid question!

Ciaran.

+------------------------+-----------------------------------------------------+
| Ciaran Treanor         | In the sleepy west of the woody east,  | P          |
| Electronic Engineering | is a valley full, full o' pioneer,     |  i         |
| Dublin City University | we're not just kids, to say the least, |   x        |
| Glasnevin              | we got ideas to us that's dear.        |    i       |
| Ireland                |             [UMass]  Black Francis (!) |     e      |
+------------------------+------------------------+---------------+------s---- +
| Voice: +353-1-7045758  | Fax: +353-1-7045508    | E-Mail: 92700217@dcu.ie    |
+------------------------+------------------------+----------------------------+
Newsgroups: comp.unix.wizards,comp.unix.admin
From: tma@encore.com (Thanh Ma)
Subject: Re: Causes Of Death On Heavily-Loaded UNIX System?
Organization: Encore Computer Corporation
Date: Wed, 16 Dec 1992 15:19:40 GMT
Keywords: system performance

kmc@netcom.com (Kevin McCarty) writes:

>In article <1992Dec15.151754.27354@ra.msstate.edu> fwp@CC.MsState.Edu (Frank Peters) writes:
>>
>[discusses performance monitoring in SunOS]

>>BIG DISCLAIMER TIME.  There are entire books written about performance
>>tuning that cover a wide variety of issues like tuning kernel
>>parameters and long term monitoring strategies.  I strongly suggest
>>buying one of them.  

>What are they?  I've already got (and read) the O'Reilly book.
>What others are there?


>-- 
>Kevin McCarty (kmc@netcom.com)

Unix System V Performance Management
Phyllis Eve Bregman & Sally A. Browning
ISBN: 0-13-016429-1
PTR Prentice Hall
(515)284-6751

thanh ma (tma@encore.com)
Newsgroups: comp.unix.wizards,alt.folklore.computers
From: peter@NeoSoft.com (Peter da Silva)
Subject: Re: So You Want To Be A Wizard? (A modest proposal)
Organization: NeoSoft Communications Services -- (713) 684-5900
Date: Mon, 14 Dec 1992 12:14:29 GMT

In article <1jlgwJ#6PNbyC9ljB052jnDYX3BKLvj=esr@snark.thyrsus.com> esr@snark.thyrsus.com (Eric S. Raymond) writes:
> I earned my wizard hat in late '83, early '84, administering a VAX 750 under 
> BSD 4.1 (the BSD nobody remembers...).

4.1A, B, or C?

I think one of them is the release that had my Star Trek game in it. Anyone
still got a tape? I'd like to get the source to that program (/usr/games/stuck)
back (I left it behind when I left Berkeley).
-- 
Peter da Silva.  <peter@sugar.neosoft.com>.
 `-_-'   Oletko halannut suttasi tnn?
  'U`    
Tarjoilija, tm ateria el viel.
Newsgroups: comp.unix.wizards,alt.folklore.computers
From: fjh@munta.cs.mu.OZ.AU (Fergus James HENDERSON)
Subject: Re: So You Want To Be A Wizard? (A modest proposal)
Organization: Computer Science, University of Melbourne, Australia
Date: Sat, 12 Dec 1992 13:13:03 GMT

esr@snark.thyrsus.com (Eric S. Raymond) writes:

>I earned my wizard hat [...]

Ah! A self-proclaimed wizard!
Isn't that a contradiction in terms?

-- 
Fergus Henderson             fjh@munta.cs.mu.OZ.AU      
This .signature virus is a self-referential statement that is true - but 
you will only be able to consistently believe it if you copy it to your own
.signature file!
Newsgroups: comp.unix.wizards,comp.unix.admin
From: duane@anasazi.com (Duane Morse)
Subject: Re: select function
Organization: Anasazi, Inc.  Phoenix, Arizona USA
Date: Sun, 13 Dec 1992 23:51:01 GMT

Regarding "select" under 386/IX, you need to use libinet.a.
-- 

Duane Morse	e-mail: duane@anasazi.com
(602) 861-7609
Newsgroups: comp.unix.wizards,alt.folklore.computers
From: wmark@msw (Mark S. Winsor)
Subject: Re: So You Want To Be A Wizard? (A modest proposal)
Organization: ProVAR
Date: Thu, 17 Dec 1992 18:20:51 GMT

pt@geovision.gvc.com (Paul Tomblin) writes:
> fjh@munta.cs.mu.OZ.AU (Fergus James HENDERSON) writes:
> >esr@snark.thyrsus.com (Eric S. Raymond) writes:
> >>I earned my wizard hat [...]
> 
> >Ah! A self-proclaimed wizard!
> >Isn't that a contradiction in terms?
> 
> Only if you're a 14 year old self-proclaimed wizard - and you proclaim it in
> your signature so that you can annoy the real wizards with every single
> posting you make.
> 
> (And no - I'm not self-proclaiming myself - I'm a couple of steps below
> wizard for now)

According to the intro, you shouldn't post here unless you ARE a wizard,
therefore every article in here is from a self-proclaimed wizard, except
myself of course :-). (I just love a good paradox!)

-- 
                                __                
email: wmark@wb3ffv.ampr.org   '  )--,--,          /       Mark S. Winsor 
                                 /  /  / __.  __  /__,     Systems Analyst
#include <stddisclaimer.h>      /  /  (_(_/|_/ (_/ \_      ProVAR, Inc.
From: guy@Auspex.COM (Guy Harris)
Newsgroups: comp.unix.wizards
Subject: Re: /dev/null and file locking
Date: 17 Dec 92 00:29:13 GMT
Distribution: na
Organization: Auspex Systems, Santa Clara

>Can two processes write both these devices simultaneously without problems?

Yes, but in most if not all implementations of UNIX, they'll have
separate inodes/vnodes; the driver may or may not properly keep track of
both streams of data, so it's not clear how they'll get interleaved.

:-)

>What happens when two processes try to lock /dev/null and /dev/another_null?
>
>My guess is the locking is done at the inode level and each will have a
>successful lock.

Inode or vnode or equivalent level; that should be true on most if not all
flavors of UNIX.
Newsgroups: comp.unix.wizards
From: js@opus40.ix.de (Juergen Seeger)
Subject: RARP daemon for PC Unix wanted 
Keywords: RARP, Ethernet, IP, PC Unix
Organization: iX-Redaktion
Date: Tue, 15 Dec 1992 16:11:14 GMT


Does anyone know a working RARP daemon for PC Unix? I
want to set up a Sun 3/50 as X terminal W/O other Suns.




-- 
 =
|Juergen Seeger                           |    EMail:        js@ix.de   |
|iX - Multiuser Multitasking Magazin      |    FAX:   +49 511 547 47 33 |
|D-3000 Hannover 61, Helstorfer Str. 7    |    Tel.:  +49 511 547 47 23 |
From: guy@Auspex.COM (Guy Harris)
Newsgroups: comp.unix.wizards
Subject: Re: What is text, data & bss anyway?
Date: 15 Dec 92 19:34:30 GMT
Organization: Auspex Systems, Santa Clara

>In gcc the following applies:
>
>/* data */ char *s =
>/* text */           "abcd";
>/* bss  */ int i;

What does GCC do with

	const char foo[] = "abcd";

I.e., does it put it in the text or data segments?  (Text segment, I
hope.)

>copy-on-write is a cheating system where data, heap, stack or, bss
>segments are marked read only on forking and copied only when one or
>the other process writes to them. It is used to avoid copying data on
>forking as the child process usually doesn't do much work, it basically
>just exec's another program.

Actually, copy-on-write is, at least in some systems, not directly
related to forking; that just happens to be one place where it buys you
something.  It may also be used, for example, to:

	1) let you set a breakpoint in a process running a shared-text
	   program or using a shared library, without screwing over
	   anybody else using that program or library (the attempt to
	   write the breakpoint causes a copy to be made; the process
	   with the breakpoint uses the modified copy, and everybody
	   else uses the unmodified copy);

	2) allow the run-time loader to do relocation by modifying the
	   text of a program or shared library (SunOS 4.x, SVR4 - you
	   want to try to avoid having this happen, in general, as it
	   reduces the amount of sharing).

Also, in most systems these days, the entire segment isn't copied, just
the pages that are actually written to.
From: shwake@nearside.UUCP (Raymond Shwake)
Newsgroups: comp.unix.wizards
Subject: Re: O Wizards, is there vi w/out shell?
Date: 16 Dec 92 13:57:56 GMT
Organization: A/C International

dkeisen@leland.Stanford.EDU (Dave Eisen) writes:

>>How about setting the SHELL environment variable to something like
>>/bin/false.  Don't know about other Unixs, but this appears to work
>>for both vi and gnuemacs on the Ultrix system that I posted this from.

	I like to set SHELL to /bin/echo; the only point is to invoke
	something innocuous.

>This doesn't do any good. The user can still type :set shell=/bin/csh
>and give himself a shell whenver he wants. The SHELL environment
>vaiable is only used to initialize the internal vi shell variable.

	Quite true. What I've done is binary patch the "set" string to
	include an embedded space (like "s x"). Seems to work.
-- 

uunet!media!ka3ovk!nearside!shwake			shwake@rsxtech
Newsgroups: comp.unix.wizards,alt.folklore.computers
From: bogstad@blaze.cs.jhu.edu (Bill Bogstad)
Subject: Re: So You Want To Be A Wizard? (A modest proposal)
Organization: Johns Hopkins Computer Science Department, Baltimore, MD
Date: Tue, 15 Dec 1992 19:47:02 GMT

[Bring back the line eater bug!!!]

In article <BzAvBJ.6q7@NeoSoft.com> peter@NeoSoft.com (Peter da Silva) writes:
>In article <1992Dec14.080551.12999@blaze.cs.jhu.edu> bogstad@gauss.cs.jhu.edu (Bill Bogstad) writes:
>>  [Minix] It's legally available and is probably as similar to modern
>> Unix kernels as the V6 kernel described in the Lions books anyway.
>
>I doubt it. It's a flakey microkernel with separate kernel-level tasks for
>the file system, memory management, and so on. Quite unlike any traditional
>UNIX kernel. ...

	I should have been more precise.  Minix provides about the same
level of functionality as V6/V7 and implements what I consider to be the
core of Unix.  I think that it's much more suitable for someone initially
learning about Unix-like systems and their implementations.  It also has the
distinct advantage that it has a book that goes section by section through
the code.  The other Unix-like systems for which source code is easily
available (386BSD, BSD386, Linux, Hurd???) are considerably more complex.
Although a book has been writen about 4.2BSD, it can't go into the same
level of detail because of concerns about USL licensing.  The other
advantage of Minix is that although it is a "flakey microkernel"; it is in
fact a microkernel.  Both OSF and USL seem to be moving their kernels in
that direction and anyone interested in working with "Unix" systems for the
long term would gain from this exposure.

				Bill Bogstad

(All of the above is of course "IMHO".)
Newsgroups: comp.unix.wizards
From: dkeisen@leland.Stanford.EDU (Dave Eisen)
Subject: Re: O Wizards, is there vi w/out shell?
Organization: Sequoia Peripherals, Inc.
Date: Fri, 11 Dec 92 18:01:18 GMT

>>Well, basically, what I'm looking for is a vi text editor, or emacs
>>acting like vi, for that matter, that will NOT allow shell commands, as
>>this tends to allow people to give themselves shell access when they should
>>not really have it -- in a Unix BBS situation.  Does anyone know how you
>>would do this?

>How about setting the SHELL environment variable to something like
>/bin/false.  Don't know about other Unixs, but this appears to work
>for both vi and gnuemacs on the Ultrix system that I posted this from.

This doesn't do any good. The user can still type :set shell=/bin/csh
and give himself a shell whenver he wants. The SHELL environment
vaiable is only used to initialize the internal vi shell variable.

The only way I know of to do what you want it to patch the binary
to prevent the user from setting his shell. And I'm not even 100%
sure that will work.

Hey UNIX vendors out there!

What the poster wants to do is a common and very reasonable
request. There are many times when you want to give users
access to an editor or a mail reading program or a pager,
but you don't want to give him access to all of the commands
on the system.

Why not add an option to vi to tell it not to allow shell
escapes?



-- 
Dave Eisen                               Sequoia Peripherals: (415) 967-5644
dkeisen@leland.Stanford.EDU              Home:                (415) 321-5154
       There's something in my library to offend everybody. 
          --- Washington Coalition Against Censorship
Newsgroups: comp.unix.wizards