View text in terminal with specific patterns highlighted

I want to view text (could be a file or a piped command output) in the terminal, but I would like to highlight a specific pattern in the text with colors, similarly to how grep highlights the pattern match in its output lines.

The reason why I can't use standard grep "pattern" /path/to/file here is because I want to view the entire text (ideally scrollable as if piped through less) and not just the lines containing the pattern.

Actually, this can be done very easily with some grep parameters.

The magic command you are looking for is:

grep --color -E "test|$" yourfile

Here's some sample output:

Full disclosure: That command was taken from this answer.

If you're not stuck on color highlighting, you could use less itself e.g.

less +g -p PATTERN file

or

less +g +/PATTERN file

The +/PATTERN highlights all instances of PATTERN in file, and the +g suppresses the default behavior of scrolling to the first match.