Grep

  is a command-line utility for searching plain-text data sets for lines that match a regular expression. Its name comes from the ed command g/re/p (globally search for a regular expression and print matching lines), which has the same effect. was originally developed for the Unix operating system, but later available for all Unix-like systems and some others such as OS-9.

Options

 * -v is the only option, which eliminates entries matching the pattern instead of giving you them