I want to append a string on the every line from the grep result. 

For example, this command will return several lines:

```
ls -a | grep "filename"

```

For example:

```
filename1
filename2
filename3
filename4

```

How can I append a string `test` on each return line using a single command? So that I get this output:

```
test filename1
test filename2
test filename3
test filename4

```