bash - Can't remove first two encode characters using text editors in linux

When I use text editor for seeing content of file a.csv it shows me:

aaa bbb ccc ddd eee fff ggg hhh iii jjj kkk

But when I cat it I have:

��aaa   bbb ccc ddd eee fff ggg hhh iii jjj kkk

So when I want to remove first to characters �� I can't do that. For example:

cat a.csv | sed 's/\(.\{2\}\)//'

The result is:

��aa    bbb ccc ddd eee fff ggg hhh iii jjj kkk

Answer

This looks like a byte order mark that's prepended to your text.

If that is correct, you can fix this by converting your file to an encoding that doesn't use a byte order mark (for example plain UTF-8), and these two characters should be gone.

How you change the encoding of a file depends on the editor you use, in vim the command to use is :set nobomb.