linux util, expand , tab 2 space

expand -t 4 src.java > src2.java

 

find . -name '*.java' ! -type d -exec bash -c 'expand -t 4 "$0" > /tmp/e && mv /tmp/e "$0"' {} \;

( https://stackoverflow.com/questions/11094383/how-can-i-convert-tabs-to-spaces-in-every-file-of-a-directory )