GNU sed VS GNU M4

sed (stream editor) is a Unix utility that parses text and implements a programming language which...

GNU M4 is an implementation of the m4 macro preprocessor.

Stream editing
GNU sed allows for powerful stream editing directly from the command line, enabling users to perform basic text transformations on an input stream (a file or input from a pipeline) without opening a text editor.
Scriptable and Automatable
It allows the creation of compact scripts that facilitate the automation of repetitive text processing tasks, making it very useful in shell scripting and larger automation workflows.
Regular Expressions
Supports robust regular expressions, which provide a powerful way to search and manipulate text, greatly enhancing its flexibility and utility for various text processing tasks.
Cross-platform
As part of the GNU project, GNU sed is available on many UNIX-like systems as well as Windows, ensuring consistency across different platforms where Unix utilities are used.
Performance
GNU sed is optimized for speed and efficiency, making it suitable for processing large volumes of text quickly on the command line.

Steep Learning Curve
Beginners might find GNU sed's syntax and regular expressions challenging to master, which could be a barrier to effectively using its full potential.
Limited editing capabilities
While very powerful for line-by-line operations and basic text transformations, sed lacks the capability to perform complex text manipulations or support for multi-line processing without complex workarounds.
Readability
Scripts written in sed can quickly become hard to read and maintain, especially for those unfamiliar with the syntax, which can lead to difficulty in debugging or later modifications.
Lack of advanced features
Compared to more comprehensive text processing tools, such as awk or modern languages like Python, sed has fewer built-in functions and lacks advanced text processing capabilities.

Portability
GNU M4 is highly portable and can run on almost any Unix-like operating system, which makes it versatile for various environments.
Macro Capabilities
It offers powerful macro processing features that are useful for a wide range of text processing tasks, such as configuring scripts, code generation, and templating.
Simplicity
M4 is relatively simple to use for basic macro processing tasks, which makes it accessible to new users and suitable for straightforward applications.
Integration
GNU M4 often integrates well with other tools and scripts, making it a useful component in build systems and automated workflows.

Limited Built-in Functions
Compared to more modern scripting languages, M4 lacks a wide range of built-in functions and features, which may limit its use for more complex tasks.
Steep Learning Curve
While simple tasks are easy to set up, mastering M4 for more advanced uses can require a deeper understanding of its syntax and capabilities.
Debugging Difficulty
Debugging macros in M4 can be challenging, especially for large scripts, due to the lack of advanced debugging tools and support.
Performance Considerations
For very large and complex scripts, performance may become an issue, as M4 is not optimized for handling large-scale data manipulation compared to more modern alternatives.