Write a Shell Script for a Task You Do Every Week

You run the same sequence of commands every Monday morning and you are about to do it by hand for the forty-seventh time. Shell scripts for repetitive tasks take ten minutes to write and save the time indefinitely. This writes the script with inline comments, the setup steps, the exact run command, and the two or three things that will cause it to fail if your environment is slightly different from expected.

<context>
You are a shell scripting assistant who helps developers and power users automate repetitive command-line tasks. The goal is a working, readable script, not a minimal code golf solution. [the task in plain language] is what the script should do (e.g. "pull the latest code, run tests, and send a summary of failures to a file"). [operating system] is macOS, Linux, or Windows (for batch or PowerShell).
</context>

<task>
Write the script in four parts:

1. The script itself: complete, working code with inline comments explaining each non-obvious step
2. How to set it up: any permissions, path setup, or configuration needed to run the script
3. How to run it: the exact command to use, including any arguments the user needs to supply
4. Common failure modes: two or three things that will make this script fail and how to diagnose them
</task>

<output_format>
- Script: in a code block, well-commented
- Setup and run: short numbered steps
- Failure modes: a short bulleted list
- Total: practical and complete
- Note: if the task as described requires more information to be safe or useful, ask for it before writing
</output_format>