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From: amitc@cbnewsl.ATT.COM (amit.chatterjee)
Newsgroups: comp.unix.questions
Subject: Re: problems with ps(1)
Summary: Re: ps unlink()
Keywords: ps unlink()
Message-ID: <2840@cbnewsl.ATT.COM>
Date: 10 Nov 89 20:15:56 GMT
References: <269@zeek.UUCP>
Organization: AT&T Bell Laboratories
Lines: 55

In article <269@zeek.UUCP>, rick@zeek.UUCP (Rick Wilhelm) writes:
> 
> When I run ps(1) I get the following results
> 
> $ ps 
> ps: unlink() failed
> ps: /etc/ps_data, Permission denied
> ps: Please notify your System Administrator
>    PID TTY      TIME COMMAND
>   6237 pts010   0:00 ksh
>   6825 pts010   0:10 ps
> $  
> 
> This problem happens sporadically, with no _apparent_ causes.
> Anyone have any ideas?  I RTFM but to no avail.
> 
> System:  AT&T 6386 WGS running System V/386 Release 3.2
> with KornShell Version 06/03/86a 386 Release 1.1
> 
> Thanks,
> 
> rick
> -- 

	The problem is actually very simple, the cause as to why this 
	ever happens is unknown to me. Anyway, the easy stuff first.

$ ls -ld /etc
drwxrwxr-x  16 root     sys         2736 Nov 10 14:51 /etc
$
$ ls -l /bin/ps
-r-xr-sr-x   1 bin      sys        21788 Nov 14  1988 /bin/ps

	As you can see, ps has setgid to sys. It tries to unlink a
	file called /etc/ps_data which requires write permission on
	/etc. /etc has write permission for its group. This is when
	all is well.

	Now when the problem you describe happens, if you take a look
	at /etc's permissions, you will notice that the group ownership
	of /etc changes from sys to bin, like below:

drwxrwxr-x  16 root     bin         2736 Nov 10 14:51 /etc

	In this case ps cannot write in /etc and you get this error.

	What I would like to know from any wizard out there, what causes
	the group ownership to change on /etc. I have this problem
	once in a while on AT&T 3B2 machines running UNIX System V Rel 3.2.

=======================================================================
	Amit Chatterjee			(201) 271-1130
	AT&T CSIL			{major gateway}!tarpon!amit
	Somerset, NJ			amit@tarpon.att.com
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