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+# The `grep` command
+
+The `grep` filter searches a file for a particular pattern of characters, and displays all lines that contain that pattern.
+grep stands for globally search for regular expression and print out. The pattern that is searched in the file is referred to as the regular expression.
+
+### Examples:
+
+1. To search the contents of the destination.txt file for a string("KeY") case insensitively.
+
+```
+grep -i "KeY" destination.txt
+```
+
+2. Displaying the count of number of matches
+
+```
+grep -c "key" destination.txt
+```
+
+3. We can search multiple files and only display the files that contains the given string/pattern.
+
+```
+grep -l "key" destination1.txt destination2.txt destination3.xt destination4.txt
+```
+
+4. To show the line number of file with the line matched.
+
+```
+grep -n "key" destination.txt
+```
+
+5. If you want to grep the monitored log files, you can add the `--line-buffered` to search them in real time.
+
+```
+tail -f destination.txt | grep --line-buffered "key"
+```
+
+### Syntax:
+
+The general syntax for the grep command is as follows:
+
+```
+grep [options] pattern [files]
+```
+
+### Additional Flags and their Functionalities:
+
+| **Short Flag** | **Long Flag**          | **Description**                                                                                 |
+| :------------- | :--------------------- | :---------------------------------------------------------------------------------------------- |
+| `-c`           | `--count`              | print a count of matching lines for each input file                                             |
+| `-h`           | `--no-filename`        | Display the matched lines, but do not display the filenames                                     |
+| `-i`           | `--ignore-case`        | Ignores, case for matching                                                                      |
+| `-l`           | `--files-with-matches` | Displays list of a filenames only.                                                              |
+| `-n`           | `--line-number`        | Display the matched lines and their line numbers.                                               |
+| `-v`           | `--invert-match`       | This prints out all the lines that do not matches the pattern                                   |
+| `-e`           | `--regexp=`            | Specifies expression with this option. Can use multiple times                                   |
+| `-f`           | `--file=`              | Takes patterns from file, one per line.                                                         |
+| `-F`           | `--fixed-strings=`     | Interpret patterns as fixed strings, not regular expressions.                                   |
+| `-E`           | `--extended-regexp`    | Treats pattern as an extended regular expression (ERE)                                          |
+| `-w`           | `--word-regexp`        | Match whole word                                                                                |
+| `-o`           | `--only-matching`      | Print only the matched parts of a matching line, with each such part on a separate output line. |
+|                | `--line-buffered`      | Force output to be line buffered.                                                               |