Shell Programming and Scripting

Hi Guys,

I have a source file which contains significant strings amongst a lot of dross in non-uniform format, I'd like to search the input file for any examples of data from my reference file, and then output any matches to a list (text file).

I've made something that achieves this, it's just very slow (The reference file contains hundreds of entries) - Is anyone able to suggest a faster / more efficient method of achieving the below output?

Many thanks,

Gary

Code:

#script.sh
cat referencefile.txt | while read HOST
do
check=`grep $HOST input.txt | wc -l`
if [  "$check" -ne 0 ]; then
echo $HOST >> output.txt
fi
done

referencefile.txt:
hostname1
hostname2
hostname3
hostname4
hostname5
hostname6
hostname7
hostname8
hostname9
hostname10

input.txt:
random text random text hostname1 random text
random text hostname3 random text
randomtexthostname6randomtext random text

output.txt:
hostname1
hostname3
hostname6

Try this...

Code:

grep -o -f referencefile.txt input.txt

--ahamed

Sorry - Didn't work for me, this is what happened:

Code:

$ grep -o -f referencefile.txt input.txt
grep: illegal option -- o
grep: illegal option -- f
Usage: grep -hblcnsviw pattern file . . .

Modified your code... might be a little faster...

Code:

while read HOST; do
  grep $HOST input.txt >/dev/null 2>&1 && echo $HOST >> output.txt
done < referencefile.txt

--ahamed

That did seem a lot faster!
Thankyou! :-)