I started working in 2006 in a startup that make an heavy usage of Python. I quickly realize of powerfull it is, even if it was only Python 2.4. But I wasn't sure if Python will continue it's expension and I would have never believed that Python spread to this level. In 2006, there was only one way of scripting, tooling or instrumenting: shell! The situation has changed.

why bash?

Shell is a standard since the beginning of Unix because the native interface of Unix is terminal and your terminal interacts with the OS using Shell.

Bash have some advantages:

• no dependencies. It is installed by default on all distros. Most of the containers have bash
• bash is part of the skill set of every sysadmin
• basic file operations (copy, move, deletion) are simple and powerfull

Bash have some disavantages:

• syntax is not really eye candy and come directly from the dark ages of the 80's. Especially if you need arithmetic expressions or list
• function and parameters handling is really basic
• there is not extension possible except by calling an external binary
• the library concept is limited to import instruction or function with the source keyword

why python rather than bash

• it is a real programming language with objects and libraries to better structure your code
• you can debug your code using vscode for example
• you can extend Python using the Python/C Api
• the standard library includes a wide range of features that covers 95% of the basic usage
• Python is included by default in the major distros. For example CentOS come with a Python interpreter by default because its package manager (yum) is written in Python.

nowaday

In 2020, I would never recommand to use Shell except for simple and short scripts that don't need maintenance neither debugging. The following situations indicates that you should stop to use shell:

• you are using IO redirections to file and grep -v to simulate set operations
• you are writing shell scripts with more than 200 lines or more than three functions
• you are spending a lot of time to debug by adding a lot echos
• you are thinking to split your shell script into different libraires and use source to include
• you are calling binaries or other shell scripts with sensitive parameter like --password

I know the power of usage and I know that people are often reluctant to change. But remember that it could worse if you realize your error too late. Two of the worst systems I have ever seen was made by more than 10.000 lines of code with interleaved layers of bash and Python. So if you are starting to write a new system from scratch think Python not bash.