[shr-u] update shr quite safely

[Rui Miguel Silva Seabra]

Because you launched 1 program then 4 programs in background, which
are fed to a while loop => much memory + cpu usage.

With...  opkg list_upgradable | awk '!/(kernel|Multiple)/ {print $1}'

... you now launch less 3 programs than before (two greps and one cat),
while feeding exactly the same output to the while loop. :)

If you grep then awk or awk then grep, then 99% of the time you're
uselessly greping. Awk greps better than grep, specially when you
want to transform the output :)

Also a nice read: Useless use of cat
		  http://www.google.pt/search?q=useless+use+of+cat

Rui

On Sun, Jul 26, 2009 at 09:40:26PM +0200, Davide Scaini wrote:
> he he this is the power of opensource...
> why you said that is heavy? (i just want to learn, i'm quite newbie in
> scripting and expecially using awk...)
> d
> 
> On Sun, Jul 26, 2009 at 8:29 PM, Rui Miguel Silva Seabra <rms at 1407.org>wrote:
> 
> > On Sun, Jul 26, 2009 at 07:18:07PM +0100, Rui Miguel Silva Seabra wrote:
> > > On Sun, Jul 26, 2009 at 07:49:19PM +0200, Davide Scaini wrote:
> > > >  I want to share my little bash script to update shr without distroying
> > my
> > > > existing kernel (a true 2.6.28).
> > > > It's really stupid, but maybe someone could find it interesting.
> > > >
> > > > opkg list_upgradable > upgradable
> > > >
> > > > cat upgradable | awk '{print $1}' | grep -v kernel | grep -v Multiple |
> > > > while read line
> > > >
> > > > do echo "installing pack $line"
> > > > opkg install $line
> > > > done
> > > >
> > > > I have a script called upgrade.sh and I run that one. If you don't want
> > to
> > > > update for example tangogps (or wathever) just add
> > > > grep -v tangogps |
> > > > just before "while read line"...
> > >
> > > Nice. But a little heavy on the little Neos :) May I suggest a possible
> > > alternative?
> >
> > oops a mistake, this one is corrected, though:
> >
> > opkg list_upgradable | awk '!/(kernel|Multiple)/ {print $1}' | \
> >         while read line; do
> >                echo "installing pack $line"
> >                opkg install $line
> >        done
> >
> > Rui
> >
> > _______________________________________________
> > Openmoko community mailing list
> > community at lists.openmoko.org
> > http://lists.openmoko.org/mailman/listinfo/community
> >

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