The article provides a comprehensive overview of the Unix text processing tool sed, also known as a stream editor, which is crucial for command-line text manipulation tasks, particularly when dealing with repetitive operations. sed functions by reading input text line by line, applying specified commands or conditions, and producing an output based on these instructions, making it efficient for tasks such as searching, filtering, and replacing text. It highlights sed’s versatility with examples of its various commands, like find and replace (s), print (p), and delete (d), among others, and explains its integration with other command-line tools like awk for enhanced text processing capabilities. Additionally, the text addresses sed’s compatibility with scripts both as standalone files and as command-line arguments, and notes the differences between GNU sed and BSD sed, particularly for macOS users. The article concludes by emphasizing the power and flexibility of sed in streamlining text processing tasks and its potential for integration with other tools like Earthly for reproducible build processes.