I am putting together a presentation for a non-technical audience. I have a program running in bash that outputs a continuous stream of values, a few of which are important. I would like to highlight the important results as they are displayed so the audience can get an idea of their frequency. The issue is that I can't get `sed` to operate on a running stream. It works fine if I put the results in a file, as in:

```
cat output.txt | sed "s/some text/some text bolded/"

```

But if I try the same thing on the running output, like this:

```
command | sed "s/some text/some text bolded/"

```

`sed` does nothing. Any thoughts? 

As Lambert was helpful enough to point out, my saying that `sed` does nothing was vague. What is happening is that the program outputs to `stdout` (I'm pretty sure it's not writing to `stderr`) as it normally would, even if it's piped through `sed`.

The issue seems to be that the command calls a second program, which then outputs to stdout. There are a few lines printed by the first program; these I can edit. Then there is a stream of values printed by the second program; these I cannot edit.

Perl and awk methods do not work either.