Conditionals

Conditionals control execution flow based on test results.

• if-then-else:

if [ $age -ge 18 ]; then
  echo "Adult"
else
  echo "Minor"
fi

• test or [ ] evaluate expressions.
• [[ ]] offers extended tests (pattern matching, regex).
• case matches patterns:

case $option in
  start) echo "Starting";;
  stop) echo "Stopping";;
  *) echo "Unknown";;
esac

Input:

age=20
if [[ $age -ge 18 ]]; then
  echo "Adult"
else
  echo "Minor"
fi

Output:

Adult

Explanation: [[ $age -ge 18 ]] checks numeric comparison.

References:

• https://man7.org/linux/man-pages/man1/bash.1.html

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