Help with regex Okay, this is almost a pure duplicate ... with one little piece of information that I just don't understand. The original question is: Sed Explanation: sed '/./,$!d' file And relates to the following: sed '/./,$!d' file The explanation at that question is really good except for one thing (and I don't have the reputation to post a comment to the answer to ask for an expansion). what is the meaning of the comma? I know this seems like a waste (a whole new question) but I have not been really able to figure it out otherwise (regex documentation argh! lol).

A comma in sed separates so called addresses in the address range.

`/./,$` means "From a line containing a character to the last line".