In a recent blog post, I made a passing comment about using Git's "dry run" option when cleaning up untracked files. That suggestion wasn't random - it stems from some hard lessons learned over the years. The kind of lessons that make you develop a healthy respect for commands that can't be undone. Let me tell you why.
Back in 2003, I watched a coworker's face turn the kind of pale you usually only see in vampire movies. He'd just run what should have been a routine UPDATE statement against our production database. There was just one tiny problem - he'd forgotten the WHERE clause. In an instant, every single order in our customer system was marked as "Processed". There was no undo button, no Ctrl+Z magic that could save us. Just the growing realization that we were in for a very long night of database restores.
That day left an indelible mark on my coding psyche. From then on, I developed an almost religious devotion to testing destructive operations before running them for real. Here's what it looked like in practice:
BEGIN TRANSACTION
UPDATE CustomerOrders
SET Status = 'Processed'
WHERE OrderDate = '2003-06-15'
-- Let's see what we actually changed
SELECT OrderID, Status, OrderDate, CustomerName
FROM CustomerOrders
WHERE OrderDate = '2003-06-15'
ROLLBACK TRANSACTION
This pattern - preview the change, verify it looks right, then either commit or run away screaming - has saved my bacon more times than I can count. And while I don't write as much SQL these days, that same principle has become a cornerstone of my development workflow.
Just last month, I was cleaning up a massive project directory with dozens of *.py files and various virtual environments cluttering things up. My finger was hovering over enter after typing git clean -fdx, when that old database lesson flickered in my brain. I backspaced and added the -n flag:
$ git clean -n
Would remove venv/
Would remove src/__pycache__/
Would remove important_config_that_should_not_be_deleted.yml
Well. That last file definitely wasn't supposed to be there. One quick git add later, and I was able to clean up the directory without accidentally nuking a crucial config file. Different decade, same principle: look before you leap.
Every developer has probably had that moment of panic after running git clean and watching important files vanish. But add a -n flag, and suddenly you get a preview of what's about to be obliterated. It's like having a time machine that lets you peek at your future mistakes.
The same goes for Python package management. I can't tell you how many times I've avoided dependency hell by first running:
pip install tensorflow --no-deps --dry-run
or when using conda:
conda install --dry-run numpy pandas
These commands let you see what chaos you're about to unleash on your carefully curated virtual environment before actually pulling the trigger.
Now, I could go on listing every tool that offers a dry-run option (and there are plenty), but that would turn this into exactly the kind of documentation no one reads. Instead, I'll offer this piece of hard-won wisdom:
Whenever you're about to run a command that makes changes - especially destructive ones - take a moment to check if there's a way to preview those changes first.
This isn't just about being paranoid (though a healthy dose of paranoia has never hurt any developer). It's about developing a mindset that values understanding what's about to happen over just making it happen. It's the difference between "let's see what this does" and "let's make sure this does what we think it will."
These days, I instinctively reach for the dry-run option first, especially when working with unfamiliar commands or in production environments. It's not that I'm any less likely to make mistakes - I just prefer to make them in a consequence-free preview rather than in production at 4:30 on a Friday afternoon.
Remember: in the world of software development, looking before you leap isn't just good advice - it's a survival strategy. And if anyone tells you they've never needed a dry run, they're either lying or the ink on their resume isn’t dry.
Got your own "I wish I'd used a dry run" story? Drop it in the comments. Misery loves company, especially the kind that teaches valuable lessons!