Filter Output (Grep Command)

1. Grep: (global regular expression print) : The grep filter searches a file for a particular pattern of characters, and displays all lines that contain that pattern. The pattern that is searched in the file is referred to as the regular expression.
grep [options] pattern [files]

• Options Description
  -c : This prints only a count of the lines that match a pattern
  -h : Display the matched lines, but do not display the filenames.
  -i : Ignores, case for matching
  -l : Displays list of a filenames only.
  -n : Display the matched lines and their line numbers.
  -v : This prints out all the lines that do not matches the pattern
  -e exp: Specifies expression with this option. Can use multiple times.
  -f file : Takes patterns from file, one per line.
  -E : Treats pattern as an extended regular expression (ERE)
  -w : Match whole word
  -o : Print only the matched parts of a matching line, with each such part on a separate output line.
• -A n : Prints searched line and nlines after the result.
  -B n : Prints searched line and n line before the result.
  -C n : Prints searched line and n lines after before the result.