GREP Cheat Sheat

Here’s a usage cheat sheet for the grep command in Linux, covering basic to advanced usage:

Basic Usage:

• Syntax: grep pattern filename

Examples:

1. Search for a String in a File:

   grep "pattern" filename

2. Search for Multiple Patterns in a File:

   grep -e "pattern1" -e "pattern2" filename

3. Search for a String in Multiple Files:

   grep "pattern" file1 file2 file3

Advanced Usage:

1. Search Recursively in Directories:

   grep -r "pattern" directory

2. Case-Insensitive Search:

   grep -i "pattern" filename

3. Display Line Numbers with Matching Lines:

   grep -n "pattern" filename

4. Display Only Matching Parts of Lines:

   grep -o "pattern" filename

5. Invert Match (Exclude Lines Matching Pattern):

   grep -v "pattern" filename

6. Count Number of Matching Lines:

   grep -c "pattern" filename

7. Display Matching Lines with Context:

   grep -A num "pattern" filename  # Display num lines after matching line
   grep -B num "pattern" filename  # Display num lines before matching line
   grep -C num "pattern" filename  # Display num lines before and after matching line

8. Recursive and Case-Insensitive Search:

   grep -ri "pattern" directory

9. Search for Whole Words Only:

   grep -w "pattern" filename

10. Search for Lines That Begin/End with Pattern: grep "^pattern" filename # Lines beginning with pattern grep "pattern$" filename # Lines ending with pattern
11. Search for Lines Matching a Regular Expression: grep -E "regex_pattern" filename
12. Search for Lines Not Matching a Regular Expression:
    grep -Ev "regex_pattern" filename

Remember, grep is a powerful tool for searching text files, and mastering its various options can greatly enhance your productivity when working in the Linux command line.