Bash Syntax Error Near Unexpected Token Fix

In this tutorial, you'll learn about Bash Syntax Error Near Unexpected Token Fix. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

Bash raises syntax error near unexpected token when the script contains unclosed quotes, missing semicolons, misplaced parentheses, or Windows carriage return characters.

The Wrong Way

for i in 1 2 3
do
  echo $i
done

Output:

bash: syntax error near unexpected token `done'

The do keyword needs to be on the same line as for or preceded by a semicolon.

The Right Way

for i in 1 2 3; do
  echo $i
done

Place do on the same line as for separated by a semicolon.

Step-by-Step Fix

1. Check for Windows line endings

cat -v script.sh | head -5
# If you see ^M$, fix with:
sed -i 's/\r$//' script.sh

2. Fix unclosed quotes

# Wrong
echo "Hello world

# Right
echo "Hello world"

3. Add missing semicolons

# Wrong
for i in 1 2 3; do echo $i done

# Right
for i in 1 2 3; do echo $i; done

4. Check bracket and parenthesis balance

# Wrong
if [ $x -eq 1
then
  echo "yes]
fi

# Right
if [ $x -eq 1 ]; then
  echo "yes"
fi

5. Use shellcheck to find syntax errors

shellcheck script.sh

Prevention Tips

• Write scripts in a proper code editor with syntax highlighting.
• Use bash -n script.sh to check syntax without executing.
• Use shellcheck to catch common syntax errors automatically.
• Avoid Windows editors that add carriage return characters.
• Keep do and then on the same line as the control structure.

Common Mistakes with syntax error

1. Forgetting deriving (Show, Eq) on custom data types needed for debugging
2. Placing the wildcard pattern first in case expressions, making all subsequent patterns unreachable
3. Using head and tail instead of pattern matching, causing runtime errors on empty lists

These mistakes appear frequently in real-world BASH code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

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