How to replace "/" with "\ /" in unix-solaris

Question

For example : 3/12/1991 should get converted to 3\/12\/1991.

That is, I want to replace / with \/ [slash with backslash and slash].

Answer 1

sed 's|/|\\/|g', maybe?

echo 3/12/1991 | sed 's|/|\\/|g'
3\/12\/1991