I have a text file with this ending:

```
line1^I$^M$
line2^I$^M$
line3^I$^M$

```

I have trying many options I found in the web by using `sed` command and even 'dos2unix' but they only work to remove the `^M$` but not `^I`. So my file is now like this:

```
line1^I$
line2^I$
line3^I$

```

I have scrutinized in the web but there is nothing about `^I`. What exactly does it mean?