• Use syntax highlighting to spot syntax errors
• Missing or unexpected tokens
  • Don't forget ; and to close if and loops.
• Quote expansions in test to avoid errors
  • [ "$number" = 1 ]
  • ALWAYS enclose variables and command substitutions in double quotes unless word splitting is needed.
• Logical Errors
• Incorrect conditional expressions
• "Off by one" errors. counters in loops
• Unanticipated situations Program encounters data or situations unforeseen.