Fix: Maintainer script make /etc/shells empty

[hongquan]

Fix #58

[github-actions]

Here's the comprehensive review of the code changes:

Script Analysis

• Improved error handling in format_error with proper empty check before processing
• Replaced cat /etc/shells with open /etc/shells for better Nu-native file handling
• Fixed newline handling in add-shells function to prevent malformed file appends
• Added proper file termination handling in remove-nu-from-shells to maintain valid file format
• Modified test assertion in test nu is not the only shell to be more flexible (from >1 to >0)
• Better structured data flow in shell manipulation operations

Security Review

• ❗ Potential security issue in test Nu version is correct where it runs external nu --version without sanitization
• ❗ All /etc/shells modifications require root privileges but don't validate execution context
• ⚠️ File operations don't include error handling for permission failures
• ✅ Improved security in file handling by using Nushell's builtin open instead of external cat

Optimization Suggestions

• ✅ All instances of cat replaced with builtin open for better performance
• ✅ File operations now handle edge cases (newlines) more efficiently
• 💡 Consider adding let-env validation in main functions to ensure proper execution context
• 💡 Could use try/catch blocks for more robust error handling in file operations

Overall Quality: 4

The changes show good attention to detail in file handling and data processing, with proper Nu 0.90+ compatibility. The security fixes around builtin command usage are excellent, though some permission/context validation would make it even better. The newline handling improvements are particularly well-done.

[hustcer]

Thanks, let's give it a try