Question: I want to replace numbers followed by period at the beginning of the line:

```
1. The quick brown fox jumps over the lazy dog
12. The slow grey cat jumps over the lazy dog
234. The strong yellow lion jumps over the lazy dog

```

with `.IP number\ntext`, so the above input would lead to:

```
.IP 1
The quick brown fox jumps over the lazy dog
.IP 12
The slow grey cat jumps over the lazy dog
.IP 234
The strong yellow lion jumps over the lazy dog

```

I am using FreeBSD12.1 sed. I would prefer if solution might be reasonablily portable to Linux boxes.

This is what I have tried:

```
sed 's/^\([0-9]\)1\./\.IP \1\
/'

```

Answer: 
I believe it's not currently possible: <https://chromium.googlesource.com/chromium/src/+/HEAD/net/docs/proxy.md#proxy-credentials-in-manual-proxy-settings>

> 
> Most platforms' manual proxy settings allow specifying a cleartext
>  username/password for proxy sign in. Chrome does not implement this,
>  and will not use any credentials embedded in the proxy settings.
> 
> 
> Proxy authentication will instead go through the ordinary flow to find
>  credentials.
> 
> 
> 

Workarounds that come to mind:

* Manually create a profile with the right setup, copy the folder, and point Chrome to it via the `--user-data-dir` option.
* There are extensions that do the proxy login automatically as soon as the browser is opened.
* Spawn `stunnel` locally and put it "in the middle" (Chrome --no pwd--> stunnel --user:pwd--> real proxy). See [How to chain proxies with Firefox or Chrome?](https://superuser.com/questions/1260279/how-to-chain-proxies-with-firefox-or-chrome)

If you're curious and want to try it out (who knows, maybe Chrome will support it one day!) the URL would have been `http://username:password@127.0.0.1:8001`
When you are lacking a means of supplying the proxy with user-name and password,
you could perhaps solve this by using a two-step proxy :

1. A local proxy server on your computer without user-name and password
2. The local proxy should connect to the real external proxy using the user-name and password.

A possible solution is installing [node.js](https://nodejs.org/en/) together with
[proxy-password-automator](https://github.com/sjitech/proxy-login-automator), but this depends on your environment.

If you don't have a suitable proxy product, or if the above does not relate
to your environment, I would need more detail about the
environment to suggest a suitable one.