Searching for patterns in files using grep

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  • Essential Linux
    • File Manipulation
      • Searching for patterns in files using grep

You can instruct the Unix system to search through a file or files for a specific word, phrase, or group of characters by using the command grep (Globally search for a REgular expression and Print). For example to locate the word 'congested' in the file 'demofile' type the following:

% grep congested demofile

The output consists of all the lines in the file 'demofile' that contain the pattern for which you are searching. If the pattern contains multiple words or any character that conveys special meaning to the Unix system, such as (%,|,*,?, and so on), then the entire pattern must be enclosed in single quotes. For example to locate the lines containing the pattern 'the other thing to note' you would type the following:

% grep 'the other thing to note' demofile