A Quick Introduction to Unix/More grep examples

Anchors Beginning of line A search can be constrained to find the string at the beginning of the line with the symbol ^. Example: grep '^A' filename Finds the string A at the beginning of lines. End of line A search can be constrained to find the string at the end of the line with the symbol $. Example: grep '5$' filename Finds the string 5 at the end of lines. Counting empty lines The combination search string ^$ finds empty lines. To match any single character The meta-character . matches any single character except the end of line character. Example The input file contains these lines: one bone throne clone We search with grep '.one' filename The results are bone throne clone The first line doesn't match. To match zero or more characters The meta-character * matches zero or more occurences of the previous character. Example The input file bells containes these lines bel bell belll be bet We search with grep 'bel*' bells The results are bel bell belll be bet Example The input file is as the previous example. The . is used after the * to require at least a single character. We search with grep 'bel*.' bells The results are bel bell belll Contrast this with the previous example. Here, we match everything except be. Example The input file is as before. We search with grep 'bel.*' bells The results are bel bell belll Character lists You can use a list of characters surrounded by [ and ] which will match on any single character in the list. Example The input file is lines: This is the zero line Here y Crosses x we search with grep [xyz] lines The result is This is the zero line Here y Crosses x Example The input file is as before. we search with grep [xyb] lines The result is Here y Crosses x