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What is Shell Scripting? (Actually)

Let me be straight with you: shell scripting is just writing down commands you'd type manually, but in a file so you can run them again.

That's it.

No magic. No complexity. Just commands in a file.

But here's the thing: That simplicity is powerful.

The Shell (What You're Actually Using)​

When you open a terminal and type commands, you're using a shell. Probably bash. Maybe zsh. Doesn't matter which one for now.

The shell is what interprets your commands. It's what talks to Linux for you.

A shell script is just a file full of those commands.

That's the whole concept. Commands in a file. Run the file, run the commands.

Why Script? (The Real Reason)​

I'll give you an example.

Every Monday, I used to:

  1. SSH into three servers
  2. Check disk space
  3. Check if services were running
  4. Review logs for errors
  5. Send a report

It took 30 minutes. Every Monday. Same thing. Every time.

Then I wrote a script. Now it takes 30 seconds. Same results. Less work.

That's why you script. To stop doing the same thing over and over.

Your First Script (Let's Actually Write One)​

Open a terminal. Create a file:

nano hello.sh

Type this:

#!/bin/bash
echo "Hello, World!"

Save it. Make it executable:

chmod +x hello.sh

Run it:

./hello.sh

That's a script. You just wrote one.

The #!/bin/bash line tells Linux to use bash to run the script. The echo command prints text. That's it.

What Scripts Actually Do​

Scripts automate tasks. That's their job.

  • Install software? Script it.
  • Deploy applications? Script it.
  • Backup files? Script it.
  • Check system health? Script it.
  • Process logs? Script it.

If you do it more than once, script it.

Common Shells (Which One?)​

Bash (The Default)​

Bash is what most people use. It's everywhere. It's what you'll probably use.

My take: Start with bash. Learn it well. You can learn others later if you need to.

Zsh is what some people prefer. It has nice features. But it's not bash.

My take: Use bash for scripts. Use zsh for your interactive shell if you want. But write scripts in bash. It's more portable.

sh (The Basic One)​

sh is the basic shell. Bash is compatible with it. Mostly.

My take: Don't worry about sh. Write bash scripts. They'll work.

What Makes a Good Script?​

A good script:

  • Does one thing well - Don't try to do everything
  • Is readable - Future you will thank present you
  • Handles errors - Things break. Scripts should handle it
  • Is documented - Comments explain why, not what
  • Works reliably - Same input, same output, every time

That's it. That's what makes a good script.

The Truth About Scripting​

Scripting isn't programming. It's automation.

You're not building applications. You're automating tasks. You're solving problems.

That mindset shift matters.

Don't try to write perfect code. Write scripts that work. That solve problems. That save time.

Perfect can come later. Working comes first.

Common Uses (What You'll Actually Do)​

System Administration​

Check disk space. Monitor services. Clean up logs. Restart things.

Real example: I have a script that checks disk space on all servers and emails me if any are above 80%. Runs daily. Saves me from surprises.

Deployment​

Deploy applications. Update configurations. Roll back if needed.

Real example: My deployment script backs up the current version, deploys the new one, runs tests, and rolls back if tests fail. One command. Done.

Data Processing​

Process logs. Extract information. Generate reports.

Real example: I have a script that processes web server logs, extracts error rates, and generates a daily report. Runs automatically. I just read the report.

Automation​

Automate anything repetitive. Anything.

Real example: I automated my morning routine. Check servers. Review logs. Generate reports. All automated. I just review results.

What's Next?​

Now that you know what scripting is, let's talk about Script Structure. We'll cover the parts every script needs. The boring but essential stuff.

Or jump ahead. Your call. But understanding script structure makes everything else easier.

Personal note: My first script was terrible. It worked, but it was terrible. That's fine. Scripts don't need to be perfect. They need to work. You can make them better later.