Tips for Success

• Always quote your variables ("$var") to prevent word splitting issues with spaces
• Use parameter expansion instead of external commands like cut or sed when possible - it's much faster
• Use declare -i for variables you only use for integers to help catch errors
• Test your string operations on edge cases (empty strings, special characters)
• Remember that bash arithmetic only works with integers (no floating point)

Common Mistakes to Avoid

• Forgetting to quote variables, especially when they might contain spaces
• Trying to use floating-point math in bash arithmetic (use bc command instead)
• Forgetting that ${var#pattern} and ${var##pattern} match from the beginning
• Forgetting that ${var%pattern} and ${var%%pattern} match from the end
• Using backticks (`` `command` ``) instead of $(command) for command substitution

Best Practices

• Use parameter expansion over external commands when possible for better performance
• Handle empty variables safely using default values (${var:-default})
• Use meaningful variable names that describe their purpose
• Comment your complex parameter expansions to explain what they do
• Test for edge cases (empty strings, special characters, numeric limits)

Example: Performance Improvement

Look at how parameter expansion can dramatically improve performance in real scripts:

# Original slow version - took 3.618 seconds
# (using external commands)
for word in $(strings file.txt); do
  len=$(echo -n $word | wc -c)
  # ... rest of script
done

# Improved fast version - took only 0.06 seconds
# (using parameter expansion)
for word in $(strings file.txt); do
  len=${#word}
  # ... rest of script
done

Example: Finding the Longest Word

#!/bin/bash
# longest-word: find longest string in a file

# Explain what we're doing
echo "Finding the longest word in your files..."

for filename; do
  if [[ -r "$filename" ]]; then
    max_word=
    max_len=0
    
    # Process each word in the file
    for word in $(strings "$filename"); do
      # Use parameter expansion to get length (much faster)
      len="${#word}"
      
      # Check if this word is longer than current max
      if (( len > max_len )); then
        max_len="$len"
        max_word="$word"
      fi
    done
    
    echo "$filename: '$max_word' ($max_len characters)"
  else
    echo "Error: Cannot read '$filename'" >&2
  fi
done