Replace multiple strings using sed

How to replace multiple strings using sed?

Answer:

If you have multiple strings to replace, you can either using the "-e" option in sed, e.g.

sed -e 's/a/A/' -e 's/b/B/' < old.txt > new.txt

or, you can use a sed script file to store all the replace conditions

e.g. vi replace.sed

s/a/A/g
s/b/B/g
s/c/C/g


and execute like

sed -f replace.sed < old.txt > new.txt