bododo@localhost ~> mkdir tests
bododo@localhost ~> cd tests
bododo@localhost tests> echo "hi2" > t.txt
bododo@localhost tests> find . -name "*.txt" | sed -i 's/2/3/g'
sed: no input files
bododo@localhost tests> find . -name "*.txt" |sed -i 's/2/3/g'
sed: no input files
bododo@localhost tests> find . -name "*.txt" |xargs sed -i 's/2/3/g'
bododo@localhost tests> cat t.txt 
hi3
bododo@localhost tests>