Hello everyone!
How do you carry the lockdown? At the moment nothing bad, taking advantage of the time to do things that before didn't have enough time to do.
‘\b[Cc]olou?r\b’ \b :: boundaries, limits the word ? :: optional inclusion of this character \. :: Exactly one single character this example matches Color, color, Colour, colour Anchors '^' :: start of a string '$' :: end of a string Ranges [] :: denote the ranges Boundaries and strings'[A-Za-z]' :: any letter '[0-9]' :: any number; it could be represented as \d '[a-z_]' :: lower case character and underscore character '[349]' :: matches number 3, number 4 and number 9; it would match 34, 49 or 349 because include those numbers '[^4]' :: matches anything BUT 4 '[Ss]erver' :: matches Server and server \s :: any white space character (space, line return, tap) > \S :: NOT looking for a white space character \b :: word boundary (may include hyphen as word separator) > \B :: NOT looking for a word boundary '\ssytem' :: Matches "file system" '\bsystem' :: Matches "file system" and "file-system" '\bpop[0-9]\b' :: Matches pop2 and pop3 but not pop3s (from /etc/services file) '\bpop[0-9]\B' :: Not matches pop2 and pop3 but matches pop3s (from /etc/services file) Quantifiers 'u*' :: Matches u zero or more times 'u?' :: Matches u zero or once only (optional) 'u+' :: Matches u once or more times 'u{3}' :: Matches uuu (u 3 times) '^\s*#' :: Matches all kind of commented lines: with no space, with spaces and with tabs 'start\s*end' :: Matches all independently the spaces between 'start' and 'end' 'start\s?end' :: Matches 'start end' and 'startend' 'start\s{2}end' :: Matches the option with 2 spaces between 'start and 'end' '[a-z]{2}[0-9]{1,2}' :: Matches a postcode [ab12 7af]; {1,2} means that it could happen once or twice grep -E :: takes extended regular expressions :: egrep. RE are extended when they use {}, but not when they use [] |
