Search & Rrplace in multiple files:
perl -n -i -e ‘s/originalword/newword/i; print;’ *.properties
Where *.properties means all the files in the directory having extension .properties.
Search & Rrplace in single file:
a) sed -i s/originalword/newword/g filename.txt
b) replace originalword newword <original.txt >new.txt
Replace coomand always creats new file with new replaced string.