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X-Authentication-Warning:	slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date:	Mon, 12 May 2003 11:19:10 -0400 (EDT)
From:	Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>
Reply-To:	cygwin AT cygwin DOT com
To:	Sylvain DOT Ferriol AT imag DOT fr
cc:	cygwin AT cygwin DOT com
Subject:	Re: suggestion for cygutils - usermod (was Re: howto change home
	path in /etc/passwd)
In-Reply-To:	<1052752066.3ebfb8c2a9667@webmail.imag.fr>
Message-ID:	<Pine.GSO.4.44.0305121112360.393-100000@slinky.cs.nyu.edu>
Importance:	Normal
MIME-Version:	1.0

On Mon, 12 May 2003 Sylvain DOT Ferriol AT imag DOT fr wrote:

> Surlignage Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>:
>
> > On Mon, 12 May 2003 Sylvain DOT Ferriol AT imag DOT fr wrote:
> >
> > > Surlignage Max Bowsher <maxb AT ukf DOT net>:
> > >
> > > > Sylvain DOT Ferriol AT imag DOT fr wrote:
> > > > > Yes , because i don't want to create a shell doing this:
> > > > > grep -v $USERNAME /etc/passwd > /etc/passwd
> > > >
> > > sorry
> > > but i don't know with sed how to delete a line starting with $USER
> >
> > For the record: "sed '/'$USER':/d".  However, grep is perfectly adequate.
> > What Max was warning you about was the shell redirection mechanism.  You'd
> > be safer using something like
> >
> >   cp -p /etc/passwd /etc/passwd-bak-tmp && grep -v $USERNAME
> > /etc/passwd-bak-tmp > /etc/passwd && rm -f /etc/passwd-bak-tmp
> >
> is it better to use $USER or $USERNAME??
>
> sylvain

$USERNAME is set by Windows.  $USER is set by /etc/profile to the output
of "id -un".  They should be the same in most cases (they even seem to be
the same if "login" is used to switch user contexts from a SYSTEM-owned
shell -- go figure).  Which would be better depends on the purpose, I
guess...
	Igor

> > > > Care! That will leave you with an empty /etc/passwd.
> > > > The shell truncates /etc/passwd BEFORE grep reads it.
> > > >
> > > > > mkpasswd -l -u $USERNAME -p $HOME >> /etc/passwd
> > > >
> > > > Max.

-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_		pechtcha AT cs DOT nyu DOT edu
ZZZzz /,`.-'`'    -.  ;-;;,_		igor AT watson DOT ibm DOT com
     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

Knowledge is an unending adventure at the edge of uncertainty.
  -- Leto II


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