Incomplete logout panel

Les Mikesell lesmikesell at gmail.com
Sun Aug 28 17:23:28 UTC 2005


On Sun, 2005-08-28 at 09:31, Claude Jones wrote:
> On Sun August 28 2005 6:04 am, gb spam wrote:
> >
> > cat > /etc/sysconfig/desktop << EOF
> > DESKTOP="KDE"
> > DISPLAYMANAGER="KDE"
> > EOF
> >
> > You will need to restart X afterwards (not just log out).
> 
> I know this doesn't have anything to do with the subject, but, would you mind 
> explaining this use of 'cat'? You appear to be using it as a quick text 
> editor. When I see new ways to do stuff like this, I make an effort to 
> understand how it works, but, I'm stumped. I've read the man cat but there's 
> nothing there. I don't know where to look next. 

Cat copies input to output and defaults to reading stdin, which
defaults to being the keyboard - so it copies keyboard input
to a file simply by redirecting the output where you want it.
Unix was designed around text mode tools with the idea that
more complicated actions could be done by piping the output
of one into the input of the next, and Linux inherits this
still-functional history.  Most shell scripting involves
manipulating stdin/stdout of various tools to glue their
operations together and cat is probably the simplest of
the bunch.

And by the way, you can use control-d at the keyboard to
send a logical EOF to the program.  The <<EOF construction
is normally only used in a shell script where you want
to feed some canned text, possibly with variable
substution, to the input of a program.  If you want to
learn more about this, look at the shell (bash) man page
or shell scripting tutorials.  The possibilities of i/o
redirection, wild-card filename expansion, etc. aren't
mentioned in each program's man page because they are
universally done by the invoking shell before the program
starts.

-- 
  Les Mikesell
   lesmikesell at gmail.com





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