How to remove lines from text file not starting with certain characters (sed or grep)

Question

How do I delete all lines in a text file which do not start with the characters `#`, `&` or `*`? I'm looking for a solution using `sed` or `grep`.

Accepted Answer

Deleting lines:

With `grep`

From http://lowfatlinux.com/linux-grep.html :

The grep command selects and prints lines from a file (or a bunch of files) that match a pattern.

I think you can do something like this:

```
grep -v '^[\#\&\*]' yourFile.txt > output.txt
```

You can also use `sed` to do the same thing (check http://lowfatlinux.com/linux-sed.html ):

```
sed '^[\#\&\*]/d' yourFile.txt > output.txt
```

It's up to you to decide

Filtering lines:

My mistake, I understood you wanted to delete the lines. But if you want to "delete" all other lines (or filter the lines starting with the specified characters), then `grep` is the way to go:

```
grep '^[\#\&\*]' yourFile.txt > output.txt
```

How to remove lines from text file not starting with certain characters (sed or grep)

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