Xref: utzoo comp.lang.c:17895 comp.unix.wizards:15736
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!cs.utexas.edu!uunet!vsedev!logan
From: logan@vsedev.VSE.COM (James Logan III)
Newsgroups: comp.lang.c,comp.unix.wizards
Subject: Re: modifying parent's environment, etc.
Message-ID: <1495@vsedev.VSE.COM>
Date: 25 Apr 89 12:39:20 GMT
References: <2158@pur-phy> <1030@quintus.UUCP>
Reply-To: logan@vsedev.VSE.COM (James Logan III)
Followup-To: comp.unix.wizards
Organization: VSE Software Development Lab
Lines: 29

[Note that followups have been redirected to to comp.unix.wizards]

In article <1030@quintus.UUCP> ok@quintus.UUCP (Richard A. O'Keefe) writes:
# In article <2158@pur-phy> sho@newton.physics.purdue.edu.UUCP (Sho Kuwamoto) writes:
# >This thread got me to thinking.  I wrote a quickie program which,
# >for reasons I don't need to go into now, modified argv[i].  The
# >strangest thing happened: if you run it in the background and look
# >at it using ps, the line where it tells you what you typed in as
# >your command line changes.
# 
# Why do you think that is strange?  ps gets the information about the
# arguments of process #1234 by peeking into the address space of process
# #1234 to find out what argv[] looks like.

Under System V the arguments are stored in the character array
u_psargs[PSARGSZ] in the u structure.  The u structure is usually
read directly from the swap device based on addresses found in 
the process table.

# Note that you don't see I/O redirection, only the strings in argv[].

The I/O redirection symbols are taken care of by the shell and
stripped off before the command sees it.   

			-Jim
-- 
Jim Logan                           logan@vsedev.vse.com
VSE Software Development Lab        uucp:  ..!uunet!vsedev!logan
(703) 329-4654                      inet:  logan%vsedev.vse.com@uunet.uu.net