Optimize shell script for multiple sed replacements

Question

I have a file containing a list of replacement pairs (about 100 of them) which are used by sed to replace strings in files.

The pairs go like:

Answer 1

You can try this.

pattern=''
cat replacement_list | while read i
do
    old=$(echo "$i" | awk -F'|' '{print $1}')    #due to the need for extended regex
    new=$(echo "$i" | awk -F'|' '{print $2}')
    pattern=${pattern}"s/${old}/${new}/g;"
done
sed -r ${pattern} -i file

This will run the sed command only once on the file with all the replacements. You may also want to replace awk with cut. cut may be more optimized then awk, though I am not sure about that.

old=`echo $i | cut -d"|" -f1`
new=`echo $i | cut -d"|" -f2`