Bash/Shell Scripting

  1. Debugging and Best Practices
    1. Debugging Techniques
      1. Shell Debugging Options
        1. set -x (Execution Trace)
          1. set -v (Verbose Mode)
            1. set -e (Exit on Error)
              1. set -u (Unset Variable Error)
                1. set -o pipefail (Pipe Failure)
                2. Command-Line Debugging
                  1. bash -x script.sh
                    1. bash -n script.sh (Syntax Check)
                    2. Static Analysis Tools
                      1. ShellCheck
                        1. Installation and Usage
                          1. Common Warnings and Fixes
                          2. Debug Output
                            1. Strategic echo Statements
                              1. printf for Formatted Output
                                1. Conditional Debug Output
                                  1. Debug Functions
                                  2. Interactive Debugging
                                    1. bash Debugger (bashdb)
                                      1. Step-by-Step Execution
                                    2. Error Handling
                                      1. Exit Status Codes
                                        1. Understanding Exit Codes
                                          1. Setting Custom Exit Codes
                                            1. Checking Command Success
                                            2. Error Detection
                                              1. Testing Command Results
                                                1. Validating Input
                                                  1. File and Directory Checks
                                                  2. Error Reporting
                                                    1. Writing Error Messages
                                                      1. Logging Errors
                                                        1. User-Friendly Messages
                                                        2. Recovery Strategies
                                                          1. Graceful Degradation
                                                            1. Retry Logic
                                                              1. Fallback Options
                                                            2. Logging
                                                              1. Log File Management
                                                                1. Creating Log Files
                                                                  1. Log Rotation
                                                                    1. Log Levels
                                                                    2. Timestamping
                                                                      1. Adding Timestamps
                                                                        1. Date Formatting
                                                                        2. Structured Logging
                                                                          1. Log Format Standards
                                                                            1. Parsing Log Files
                                                                            2. System Logging
                                                                              1. syslog Integration
                                                                                1. logger Command
                                                                              2. Security Considerations
                                                                                1. Input Validation
                                                                                  1. Sanitizing User Input
                                                                                    1. Preventing Injection Attacks
                                                                                      1. Validating File Paths
                                                                                      2. File Permissions
                                                                                        1. Setting Appropriate Permissions
                                                                                          1. Temporary File Security
                                                                                            1. Avoiding World-Writable Files
                                                                                            2. Environment Security
                                                                                              1. PATH Security
                                                                                                1. Avoiding Dangerous Commands
                                                                                                  1. Privilege Escalation Prevention
                                                                                                  2. Secure Coding Practices
                                                                                                    1. Quoting Variables
                                                                                                      1. Using Full Paths
                                                                                                        1. Avoiding eval
                                                                                                      2. Scripting Best Practices
                                                                                                        1. Code Organization
                                                                                                          1. Script Structure
                                                                                                            1. Function Organization
                                                                                                              1. Configuration Separation
                                                                                                              2. Documentation
                                                                                                                1. Inline Comments
                                                                                                                  1. Function Documentation
                                                                                                                    1. Usage Examples
                                                                                                                      1. README Files
                                                                                                                      2. Naming Conventions
                                                                                                                        1. Variable Names
                                                                                                                          1. Function Names
                                                                                                                            1. File Names
                                                                                                                              1. Consistent Style
                                                                                                                              2. Code Quality
                                                                                                                                1. Idempotent Scripts
                                                                                                                                  1. Error-Resistant Code
                                                                                                                                    1. Performance Considerations
                                                                                                                                    2. Common Pitfalls
                                                                                                                                      1. Unquoted Variables
                                                                                                                                        1. Filename Spaces
                                                                                                                                          1. Useless Use of cat
                                                                                                                                            1. Bashisms in sh Scripts
                                                                                                                                              1. Word Splitting Issues
                                                                                                                                              2. Testing
                                                                                                                                                1. Unit Testing Frameworks
                                                                                                                                                  1. Integration Testing
                                                                                                                                                    1. Test-Driven Development
                                                                                                                                                      1. Automated Testing
                                                                                                                                                      2. Version Control
                                                                                                                                                        1. Git for Scripts
                                                                                                                                                          1. Branching Strategies
                                                                                                                                                            1. Release Management
                                                                                                                                                            2. Deployment
                                                                                                                                                              1. Installation Scripts
                                                                                                                                                                1. Configuration Management
                                                                                                                                                                  1. Environment-Specific Settings
                                                                                                                                                                    1. Rollback Procedures