Highlight console search output, while displaying entire command output

When I use e.g. cat file.txt | grep --color=tty "pattern" I get the pattern I search highlighted. When I want some more context around each hit, grep has the -A, -B and -C parameters.

However, I want to display the whole file (or whatever command output) and highlight a certain pattern. Does such a highlight command or tool exist?

There was an answer on unix.stackexchange.com that had this neat trick:

grep -E --color 'pattern|$' file.txt

or

grep --color 'pattern\|$' file.txt

which matches your pattern or the end-of-line on each line. Only the pattern is highlighted.

I like ack.

ack --passthru somepattern filename

It's like grep, but better. It highlights by default, and with the --passthru option it shows the entire file (or standard input) instead of only the matching lines.

I also recommend the use of less (or such), but I want to show you a more didactical solution. Once you have defined this function:

function highlight()
{
    sed "s/$1/`tput smso`&`tput rmso`/g" "${2:--}"
}

You can use it this way:

command | highlight pattern
highlight pattern file.txt

Note: This version is case sensitive, to change that just append i after g in the sed expression.