[nycbug-talk] sed Question

Jan Schaumann jschauma at netmeister.org
Thu Mar 30 19:23:33 EST 2006


Kevin Reiter <tux at penguinnetwerx.net> wrote:
> Jan Schaumann wrote:
> > Kevin Reiter <tux at penguinnetwerx.net> wrote:
> >  
> >> #!/bin/sh
> >>
> >> echo ""
> >> echo "Finding the fastest cvsup server."
> >> echo ""
> >> fastest_cvsup -c us | grep 1st | cut -d : -f 2 > server.txt
> >> sed 's/^[ \t]*//' server.txt > fast.txt
> >> fastest=`cat fast.txt`
> > 
> > You can do that without any temporary files (and one pipe less):
> > 
> > fastest=`fastest_cvsup -c us | awk '/1st/ {print $3;}'`
> > sed -e "s/host=cvsup.*FreeBSD\.org/host=$fastest/" ports-sup
> >       ^^^
> > 
> > Use regular quotes (") instead of ', otherwise the variable '$fastest'
> > won't be expanded.
> 
> Tried that, but it didn't write to the file (ports-sup):

Oh, of course not.  If you want to change the file in place do

fastest=`fastest_cvsup -c us | awk '/1st/ {print $3;}'`
sed -e "s/host=cvsup.*FreeBSD\.org/host=$fastest/" ports-sup \
	> ports-sup.tmp && mv ports-sup.tmp ports-sup

Or generate input for and pipe it right to: ed(1).  (Left as an exercise
for the reader. :-)

-Jan

-- 
The reader is encouraged to add smileys where necessary to increase
positive perception.  Right here might be a good place:
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