Bash Script Regular Expressions…How to find and replace all matches?

Question

I am writing a bash script that reads a file line by line.

The file is a .csv file which contains many dates in the format DD/MM/YYYY but I would like to change the

Answer 1

You can do it using sed

echo "11/12/2011" | sed -E 's/([0-9][0-9]?)\/([0-9][0-9]?)\/([0-9][0-9][0-9][0-9])/\3-\2-\1/'