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•Arnošt Havelka

Premium: Bash Script Automation

Combine loops and conditionals to build scripts that run tasks automatically and respond to system state.

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Premium: Bash Script Automation

Loops and conditionals are the backbone of automation. Master them and you'll write scripts that handle complex workflows effortlessly.

Step 1: Loop Over a List

Terminal
~$for server in web app db; do echo $server; done

The for loop iterates over a list. One line replaces three.

Step 2: Loop Over Files

Terminal
~$for file in *.log; do wc -l $file; done

Process files in batch. No need to run commands individually.

Step 3: Conditional Execution

Terminal
~$retries=4 if [ $retries -gt 3 ]; then echo 'Too many retries'; fi

Conditionals let your script make decisions. Check file existence, compare numbers, test conditions.

Checklist You Can Reuse

  1. Loop with for var in list; do commands; done.
  2. Use for file in *.ext to process files in batch.
  3. Test with if [ condition ]; then commands; fi.
  4. Comparisons: -eq (equal), -gt (greater), -lt (less), -f (file exists).

Knowledge Check

1 / 2

Which loop structure processes every .sh file in the current directory?

References

These documentation links provide authoritative details for the commands used in this article.

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Premium: Bash Script Practice

Combine variables, functions, loops, and conditionals to solve a realistic multi-step scenario.