Re: Piping within for-loops

From: Barry Margolin (barmar_at_alum.mit.edu)
Date: 02/27/05 

Date: Sun, 27 Feb 2005 09:19:06 -0500

In article <d756f1c9.0502270452.2f902ef@posting.google.com>,
 halsbrecherisch@yahoo.com (halsbrecherisch) wrote:

> Hi!
> I want to write a script, that selects words from a wordlist,
> which don't contain certain characters, e.g.
> # ./filter a b c
> lists all words that don't contain the letters a, b and c.
> I've written this script:
>
> --- begin
> cat /usr/share/dict/words |
>
> for omit in $1
> do
> if [ ! "$omit" == "" ]; then grep -v -i "$omit" ; else cat; fi
> done |
>
> tee result
> --end
>
> My problem is, that the grep only affects the piped data during the 1st
> loop of the for statement. How can I solve this?

Unless you run the script like:

./filter "a b c"

it looks to me like your script will only loop once anyway. Don't you
mean:

for omit in "$@"

?

Anyway, if you want to reread the file each time through the loop, put
the file reading inside the loop:

DICT=/usr/share/dict/words
for omit in "$@"
do
  if [ ! "$omit" == "" ]
  then grep -v -i "$omit" $DICT
  else cat $DICT
  fi
done | tee result 

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

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