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Re: suggestion for cygutils - usermod (was Re: howto change home path in /etc/passwd)


On Mon, 12 May 2003, Igor Pechtchanski wrote:

> On Mon, 12 May 2003 Sylvain.Ferriol@imag.fr wrote:
>
> > Surlignage Igor Pechtchanski <pechtcha@cs.nyu.edu>:
> >
> > > On Mon, 12 May 2003 Sylvain.Ferriol@imag.fr wrote:
> > >
> > > > Surlignage Max Bowsher <maxb@ukf.net>:
> > > >
> > > > > Sylvain.Ferriol@imag.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

Sylvain,

FYI, $USERNAME doesn't seem to be set if the user is not a "real" user,
e.g., SYSTEM:

C:\> at 11:30 /interactive c:\cygwin\bin\bash.exe --login -i

Then from the bash window:

$ set | grep '^U'
UID=18
USER=SYSTEM
USERPROFILE='C:\Documents and Settings\Default User'

> > > > > 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.

	Igor
-- 
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     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski
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Knowledge is an unending adventure at the edge of uncertainty.
  -- Leto II


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