Answer by user.dz for Show all lines before a match

FreeBSD (including MacOS) version does have such feature.

Well -B -1 works, it shows all the lines before the match from the beginning of the file.

... | grep -B -1 -- "foo"

Same for -A -1 , it shows all the lines after the match to the end of the file.

... | grep -A -1 -- "foo"

May be useful for some, It doesn't work with GNU implementation included within Ubuntu.