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From: jgy@hropus.UUCP (John Young)
Newsgroups: comp.unix.questions
Subject: Re: Destroying arguments
Message-ID: <1042@hropus.UUCP>
Date: Tue, 19-May-87 14:06:39 EDT
Article-I.D.: hropus.1042
Posted: Tue May 19 14:06:39 1987
Date-Received: Sat, 23-May-87 13:28:29 EDT
References: <292@osupyr.UUCP> <239@polyof.UUCP> <485@bene.UUCP> <6723@mimsy.UUCP> <19131@sun.uucp>
Distribution: comp.unix.questions
Organization: Bell Labs, Holmdel, NJ
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Guy Harris says:

> This really isn't a C question at all, it's a UNIX question, so I'll
> redirect it where it should have been sent in the first place.
> .........
> As do most other versions of "ps".  The 3B2 version of "ps" does it
> differently; the kernel stashes a string away in the U area that
> contains the original arguments used to invoke the program.  (I have
> no idea whether this was done because somebody thought this was the
> right way to do things, or because they couldn't figure out how to
> snarf the arguments up on a machine whose stack grows upward in
> memory....)  On this machine, you *can't* smash your argument list.
> Period.
> ......

Not true. It depends on which UNIX your running on your 3B2:

a)  On a SWAPPING system a 'ps -l' will show you
the u.u_comm field which will give you JUST the first argument (normally
the program name) of the process. This can not be changed by normal
methods from inside the process.  'ps -f' will show you what's
really pointed to by argv[0] which can be changed.

b)	On a PAGING system ONLY the first 40 bytes of arguments are copied
into the saftey of the user block (ps may not show you much more
than this anyway) so if you want arguments passed to you with some
secrecy just put them futher down the line.