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Path: utzoo!dciem!nrcaer!cognos!geovision!alastair
From: alastair@geovision.UUCP (Alastair Mayer)
Newsgroups: comp.lang.c
Subject: Re: Accessing argc & argv from a functi
Message-ID: <144@geovision.UUCP>
Date: Fri, 14-Aug-87 11:05:34 EDT
Article-I.D.: geovisio.144
Posted: Fri Aug 14 11:05:34 1987
Date-Received: Sun, 16-Aug-87 08:53:32 EDT
References: <22@flmis06.ATT.COM> <28700019@ccvaxa> <274@spar.SPAR.SLB.COM>
Reply-To: alastair@geovision.UUCP (Alastair Mayer)
Organization: Geovision Corporation, Ottawa, Canada
Lines: 41

In article <274@spar.SPAR.SLB.COM> hunt@spar.UUCP (Neil Hunt) writes:
>I have thought of another (rather silly) way to obtain the
>arguments to a program without having access to main:  :-)
>
> [.. do a ps and grep out the PID.. ]
>args, and stick the whole lot into a file:
>
>	sprintf(str, "ps -uwww | egrep %d | sed -f com > /tmp/args", getpid());
>
>Execute the command pipe using system:
>
>	system(str);
>
>Now open and read the file, and obtain the original args (which will not
>change even if your program screws up its stack and scribbles over everything).

This is similar to a method I suggested to a co-worker who needed
to do the same thing.  The refinement you missed avoids the use of a
temporary file and the need to open that file.   Just use popen(3), which
is analgous to fopen(3) except that a command is given instead of the
filename.  E.g:
	your example:  sprintf(str, ..etc..)
                   system(str);
				   /* following implied by your msg */
                   fp = fopen("/tmp/args","r");
                   fscanf(fp, ..etc..);
                   fclose(fp);

    using popen:   sprintf(str, ..etc..)
                   fp = popen(str,"r");  /* combines system and fopen, sort of*/
                   fscanf(fp, ..etc..);
                   pclose(fp);

This implies Unix (or some other implementation that supports popen(3))
but so does your version.   And of course, that [fp]open succeeded
should be checked before attempting the fscanf in real code.
-- 
 Alastair JW Mayer     BIX: al
                      UUCP: ...!utzoo!dciem!nrcaer!cognos!geovision!alastair

Let's build a base on the Moon on our way to the asteroids - forget Mars.