Invert the sense of matching, to select non-matching lines. This option is useful for passing to shell scripts that already use -i, to cancel its effects because the two options override each other.

no-ignore-caseĭo not ignore case distinctions in patterns and input data. Ignore case distinctions in patterns and input data, so that characters that differ only in case match each other. The empty file contains zero patterns, and therefore matches nothing. If this option is used multiple times or is combined with the -e ( -regexp) option, search for all patterns given. This option can be used to protect a pattern beginning with “-”. If this option is used multiple times or is combined with the -f ( -file) option, search for all patterns given. Matching Control -e PATTERNS, -regexp= PATTERNS This option is experimental when combined with the -z ( -null-data) option, and grep -P may warn of unimplemented features. Interpret PATTERNS as Perl-compatible regular expressions (PCREs). Interpret PATTERNS as basic regular expressions (BREs, see below). Interpret PATTERNS as fixed strings, not regular expressions. Interpret PATTERNS as extended regular expressions (EREs, see below). Output the version number of grep and exit. Options Generic Program Information -help If no FILE is given, recursive searches examine the working directory, and nonrecursive searches read standard input. Typically PATTERNS should be quoted when grep is used in a shell command.Ī FILE of “ -” stands for standard input. PATTERNS is one or more patterns separated by newline characters, and grep prints each line that matches a pattern. Search stdin for lines that do not match a pattern: cat path/to/file | grep -invert-match ' search_pattern'.Search for lines matching a pattern, printing only the matched text: grep -only-matching ' search_pattern' path/to/file.Print file name and line number for each match with color output: grep -with-filename -line-number -color=always ' search_pattern' path/to/file.Print 3 lines of context around, before, or after each match: grep - context|before-context|after-context= 3 ' search_pattern' path/to/file.Use extended regular expressions (supports ?, +,, () and |), in case-insensitive mode: grep -extended-regexp -ignore-case ' search_pattern' path/to/file.Search for a pattern in all files recursively in a directory, showing line numbers of matches, ignoring binary files: grep -recursive -line-number -binary-files= without-match ' search_pattern' path/to/directory.Search for an exact string (disables regular expressions): grep -fixed-strings ' exact_string' path/to/file.Search for a pattern within a file: grep ' search_pattern' path/to/file.Print lines that match patterns Examples (TL DR) The Backslash Character and Special Expressions.Character Classes and Bracket Expressions.This operator has the lowest precedence of all regular expression operators. The toggle operator | (pipe) allows you to specify different possible matches which can be literal strings or sets of expressions. To search for multiple patterns, use the OR (toggle) operator. When no regular expression type is specified, grep interprets search patterns as basic regular expressions. GNU grep supports three regular expression syntaxes, Basic, Extended and Perl compatible. Learn how to use grep more effectively by following the examples in this tutorial. In that guide, let’s show you how to use grep to find several words or string patterns. This tool prints all lines that contain the words that you specify as the search pattern. You can grep multiple strings in different files and directories. Using the grep command, you can customize how the tool looks for patterns or multiple patterns in this case. This name stands for Global Regular Expression Printing. Grep is a powerful utility available by default on UNIX-based systems.

Grep multiple patterns