linux-bash/AGENTS.md

# AGENTS.md - Agent Coding Guidelines

This document provides guidelines for agents working in this repository.

---

## Project Overview

This is a **Bash shell script** repository containing multiple independent utilities for Linux server management. Each subdirectory is a separate project.

### Subprojects

| Directory | Description |
|-----------|-------------|
| `port-info/` | Linux port information display (TCP, UDP, HTTP services) |
| `docker-info/` | Docker and server information collector |
| `database-info/` | Database information collector (WIP) |
| `systemctl-info/` | Systemd/systemctl detailed information (v2.0 modular) |
| `filebrowser/` | FileBrowser installation/uninstall scripts |
| `frp/` | FRP (Fast Reverse Proxy) management scripts |
| `openlist/` | OpenList installation/management scripts |
| `mengyamonitor/` | MengyanMonitor installation scripts |
| `user-manager/` | User management utility |
| `change-mirror/` | Mirror changing and Docker installation scripts |
| `login-info/` | Login information display |
| `ssh/` | SSH key management scripts |

---

## Build / Lint / Test Commands

### Running Scripts

```bash
# Make executable and run
chmod +x <script>.sh
./<script>.sh

# Or run with bash
bash <script>.sh
```

### Linting

Use **shellcheck** for static analysis of all Bash scripts:

```bash
# Install shellcheck (if not present)
apt-get install shellcheck          # Debian/Ubuntu
yum install epel-release && yum install ShellCheck  # RHEL/CentOS

# Run shellcheck on a specific script
shellcheck port-info/port_info.sh
shellcheck docker-info/docker-info.sh

# Run with specific severity levels
shellcheck -S error <script>.sh    # Errors only
shellcheck -S warning <script>.sh  # Warnings and errors

# Check all scripts in repository
shellcheck port-info/*.sh docker-info/*.sh systemctl-info/systemctl-info \
  filebrowser/*.sh frp/*.sh openlist/*.sh mengyamonitor/*.sh user-manager/*.sh \
  change-mirror/*.sh login-info/*.sh ssh/*.sh
```

### Syntax Validation

```bash
# Check bash syntax without executing
bash -n <script>.sh

# Validate all scripts
for f in **/*.sh; do bash -n "$f" && echo "OK: $f"; done
```

### Testing a Single Function

Bash doesn't have traditional unit tests. Test functions interactively:

```bash
# Source the script and test specific functions
source <script>.sh
function_name argument    # Test specific function

# Example: test port-to-service lookup
source port-info/port_info.sh
get_service_name 80       # Should output: HTTP
```

### Running Full Scripts

```bash
# Port info
bash port-info/port_info.sh

# Docker info (requires Docker installed)
bash docker-info/docker-info.sh

# Systemctl info (requires root for full functionality)
sudo bash systemctl-info/systemctl-info
```

---

## Code Style Guidelines

### General Bash Style

#### Shebang and Error Handling
- Always use `#!/usr/bin/env bash` or `#!/bin/bash`
- Add `set -euo pipefail` at the start of scripts for safety:
  - `-e`: Exit on error
  - `-u`: Exit on undefined variables
  - `-o pipefail`: Pipeline fails if any command fails

#### Formatting
- **Indentation**: 4 spaces (no tabs)
- **Line length**: Keep lines under 100 characters
- **Quotes**: Always quote variables: `"$variable"` not `$variable`
- Use `printf` over `echo` for complex output

### Naming Conventions

```bash
# Functions - snake_case
print_header() { }
get_server_info() { }
check_root() { }

# Variables - descriptive names
local container_output
local cpu_count
local total_mem

# Constants - UPPER_CASE
readonly RED='\033[0;31m'
readonly HEADER_COLOR="${BRIGHT_CYAN}"
```

### Variable Naming Patterns

- **Constants** (colors, separators): UPPERCASE with underscores, e.g., `RED`, `SEPARATOR`
- **Global variables**: UPPERCASE, e.g., `PORT_CMD`
- **Local variables in functions**: lowercase with underscores, e.g., `local port=$1`
- **Function names**: lowercase with underscores, e.g., `check_commands()`

### Function Structure

```bash
# Good function definition
function_name() {
    local arg1=$1
    local arg2=$2
    
    # function body
    
    return 0  # Always return explicit status
}

# Document functions with comments
# 获取服务器信息
get_server_info() {
    print_header "服务器信息"
    local cpu_count=$(grep -c '^processor' /proc/cpuinfo)
    print_key_value "CPU核心数" "$cpu_count"
}
```

### Color Variables

Define colors at the top of the script using ANSI escape codes:

```bash
# Basic colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'  # No Color - always reset at end

# Bright colors
BRIGHT_CYAN='\033[1;36m'
BRIGHT_MAGENTA='\033[1;35m'
```

### Error Handling

```bash
# Check command existence before use
command_exists() {
    command -v "$1" >/dev/null 2>&1
}

if ! command_exists docker; then
    print_error "Docker未安装"
    exit 1
fi

# Use proper exit codes
if [ "$?" -ne 0 ]; then
    echo -e "${RED}Error: command failed${NC}" >&2
    exit 1
fi
```

### Input Handling

- Prefer arguments over interactive input
- Validate inputs before processing
- Use `local` for all function parameters
- Check for required arguments

### String Comparisons

```bash
# String equality
if [ "$var" = "value" ]; then
    # ...
fi

# Numeric comparison
if [ "$num" -eq 0 ]; then
    # ...
fi

# Regex matching
if [[ "$port" =~ ^[0-9]+$ ]]; then
    # ...
fi
```

### Common Patterns

#### Command Availability Check
```bash
if command -v ss &> /dev/null; then
    PORT_CMD="ss"
elif command -v netstat &> /dev/null; then
    PORT_CMD="netstat"
else
    echo -e "${RED}Error: ss or netstat not found${NC}"
    exit 1
fi
```

#### Reading Lines Safely
```bash
while IFS= read -r line; do
    # process line
done < <(command)
```

#### Safe Variable Usage
- Always quote variables: `"$var"` not `$var`
- Use `${var}` for clarity in complex expressions
- Initialize variables before use

### Shellcheck Compliance

Run `shellcheck` and fix all warnings. Common issues:

- **SC2086**: Quote variables to prevent word splitting
- **SC2166**: Use `&&` instead of `-a` in test expressions
- **SC2027**: Quote strings containing newlines
- **SC2248**: Prefer printf over echo
- **SC1090**: Can't follow non-constant source (use explicit paths)

---

## Output Patterns

Use helper functions for consistent output:

```bash
print_header()    # Boxed titles
print_section()   # Section headers with arrows
print_key_value() # Key: Value pairs
print_success()   # Green checkmark
print_warning()   # Yellow warning
print_error()     # Red X
```

---

## Testing Checklist

Before submitting changes:

- [ ] Run `shellcheck <script>.sh` with no warnings
- [ ] Run `bash -n <script>.sh` for syntax check
- [ ] Test on a system with required dependencies
- [ ] Test on a system without optional dependencies (graceful degradation)
- [ ] Verify all color output displays correctly
- [ ] Check that tables align properly

---

## Documentation

- Use Chinese comments to match existing codebase style (most scripts are Chinese-language)
- Add section separators: `#===============================================================================`
- Document function purpose before definition
- Include usage information in comments
- Document dependencies clearly

---

## File Extensions

- Bash scripts: `.sh`
- Executable scripts may have no extension
- Service files: `.service`

---

## Subproject Guidelines

For specific subproject guidelines, see the AGENTS.md files in each subdirectory:

- [port-info/AGENTS.md](port-info/AGENTS.md)
- [docker-info/AGENTS.md](docker-info/AGENTS.md)
- [systemctl-info/AGENTS.md](systemctl-info/AGENTS.md)

---

## Dependencies

### Required (Common)
- `bash` (4.0+)
- Standard POSIX utilities: `awk`, `grep`, `sed`, `sort`, `uniq`

### Optional
- `docker` - for docker-info script
- `systemctl`, `journalctl` - for systemctl-info script
- `shellcheck` - for linting
- `jq` - for better JSON parsing

---

## Security Notes

- Some scripts require root/sudo for full functionality
- Always validate user input if adding new features
- Use proper quoting to prevent word splitting and globbing
- Sanitize any data passed to `eval` or similar dangerous operations
- Never hardcode credentials or sensitive data

---

## Common Tasks

### Adding a New Port Service (port-info)
Edit `get_service_name()` function:
```bash
get_service_name() {
    local port=$1
    case $port in
        80)     echo "HTTP" ;;
        443)    echo "HTTPS" ;;
        3306)   echo "MySQL" ;;
        9000)   echo "PHP-FPM" ;;
        *)      echo "未知" ;;
    esac
}
```

### Adding a New Module (systemctl-info)
1. Create a new function following existing patterns: `module_xxx()`
2. Add function to the module list array
3. Use consistent color scheme and formatting
4. Add documentation in the AGENTS.md

### Adding a New Utility
1. Create new directory if it's a significant project
2. Follow the code style guidelines above
3. Create an AGENTS.md for the subproject
4. Add to the project table in this file