Using sed to replace tab with spaces

Question

I'm trying to replace the tab with 4 spaces, using sed, but it is not working.

Here is my code:

sed -i '{s/\t/ \{4\}/g}' filename

Any suggestion is appreciate.

Answer 1

In sed replacement is not supposed to be a regex, so use:

sed -i.bak $'s/\t/    /g' filename

On gnu-sed even this will work:

sed -i.bak 's/\t/    /g' filename