Question: I am working on a script to configure a server. Basically the script installs several services and copies configuration files in to place.

I would like to replace the username in one of the configuration files with the content of another file.
The input file is one line of text which contains the username.
The config file has multiple lines of text but only one line refers to the username.

How do I replace the username of the config file with the username stored in the input file?

Answer: 
There's an option to toggle between the field value and the field name - in your case, it seems that LO is displaying the field name instead of the field value. You can change it on different, alternative ways:

* `CTRL`+`F9`;
* Menu "`View`" -> "`Field Names`";
* Menu "`Tools`" -> "`Options`" -> "`LibreOffice Writer`" -> "`View`" -> disable "`Field Codes`".

*(tested with LO 4.2.6.3 and Ubuntu 14.04 LTS)*
The gray background is simply there to denote a field. This background is not printed. Choose View > Field Shadings (or press Ctrl+F8) to turn this feature off.