0
# CLI Interface
1

2
XO provides a comprehensive command-line interface for linting JavaScript and TypeScript projects with zero configuration required.
3

4
## Capabilities
5

6
### Basic Usage
7

8
```bash
9
# Lint all supported files in current directory
10
xo
11

12
# Lint specific files or patterns
13
xo index.js src/*.ts test/**/*.js
14

15
# Lint with glob patterns
16
xo "src/**/*.{js,ts}" "test/**/*.spec.*"
17
```
18

19
### Auto-fixing
20

21
Automatically fix linting issues where possible.
22

23
```bash
24
# Fix all fixable issues
25
xo --fix
26

27
# Fix specific files
28
xo --fix src/index.js
29

30
# Combine with other options
31
xo --fix --space --react src/
32
```
33

34
### Formatting Options
35

36
Control code style and formatting preferences.
37

38
```bash
39
# Use spaces instead of tabs (default: 2 spaces)
40
xo --space
41

42
# Use specific number of spaces
43
xo --space 4
44

45
# Force tab indentation
46
xo --space false
47

48
# Control semicolon usage
49
xo --semicolon        # Require semicolons (default)
50
xo --no-semicolon     # Disallow semicolons
51
```
52

53
### Prettier Integration
54

55
Enable Prettier formatting integration.
56

57
```bash
58
# Format with Prettier
59
xo --prettier
60

61
# Prettier compatibility mode (disable conflicting rules)
62
xo --prettier=compat
63
```
64

65
### React Support
66

67
Enable React-specific linting rules.
68

69
```bash
70
# Enable React support
71
xo --react
72

73
# Combine with other options
74
xo --react --prettier --space 2
75
```
76

77
### Configuration
78

79
Specify custom configuration files and working directories.
80

81
```bash
82
# Use custom config file
83
xo --config ./custom-xo.config.js
84

85
# Set working directory
86
xo --cwd /path/to/project
87

88
# Combine configuration options
89
xo --config ./xo.config.js --cwd ./src
90
```
91

92
### Output Control
93

94
Control what gets displayed in the output.
95

96
```bash
97
# Show only errors (hide warnings)
98
xo --quiet
99

100
# Use specific reporter
101
xo --reporter json
102
xo --reporter compact
103
xo --reporter unix
104

105
# Print effective ESLint config for a file
106
xo --print-config=src/index.js
107
```
108

109
### Ignore Patterns
110

111
Specify files and directories to ignore.
112

113
```bash
114
# Ignore specific patterns
115
xo --ignore "dist/**" --ignore "*.min.js"
116

117
# Multiple ignore patterns
118
xo --ignore "node_modules/**" --ignore "coverage/**" --ignore "build/**"
119
```
120

121
### Editor Integration
122

123
Open files with issues directly in your editor.
124

125
```bash
126
# Open files with issues in editor
127
xo --open
128

129
# Combine with other options
130
xo --open --quiet
131
```
132

133
### Stdin Support
134

135
Lint code from standard input.
136

137
```bash
138
# Lint from stdin
139
echo "console.log('hello')" | xo --stdin
140

141
# Specify filename for context
142
echo "const x: string = 'test'" | xo --stdin --stdin-filename="test.ts"
143

144
# Fix stdin input
145
echo "console.log( 'hello' )" | xo --stdin --fix
146
```
147

148
### Version Information
149

150
```bash
151
# Show XO version
152
xo --version
153
```
154

155
## CLI Options Reference
156

157
```typescript { .api }
158
interface CliFlags {
159
  /** Automatically fix issues (default: false) */
160
  fix: boolean;
161
  
162
  /** Reporter to use for output formatting */
163
  reporter?: string;
164
  
165
  /** Space indentation configuration (string that gets parsed) */
166
  space?: string;
167
  
168
  /** Path to XO configuration file */
169
  configPath?: string;
170
  
171
  /** Show only errors, not warnings */
172
  quiet?: boolean;
173
  
174
  /** Use semicolons at end of statements */
175
  semicolon?: boolean;
176
  
177
  /** Enable Prettier integration */
178
  prettier?: boolean;
179
  
180
  /** Enable React-specific rules (default: false) */
181
  react: boolean;
182
  
183
  /** Working directory for files (default: process.cwd()) */
184
  cwd: string;
185
  
186
  /** Print effective ESLint config for file */
187
  printConfig?: string;
188
  
189
  /** Show version information */
190
  version?: boolean;
191
  
192
  /** Read code from stdin */
193
  stdin?: boolean;
194
  
195
  /** Filename for stdin input (default: "stdin.js") */
196
  stdinFilename: string;
197
  
198
  /** Open files with issues in editor */
199
  open?: boolean;
200
  
201
  /** Ignore pattern globs (can be specified multiple times) */
202
  ignore: string[];
203
}
204
```
205

206
## Exit Codes
207

208
XO uses standard exit codes to indicate the result of linting:
209

210
- **0**: No errors found (warnings may be present)
211
- **1**: Errors found or linting failed
212

213
## Examples
214

215
### Common Development Workflows
216

217
```bash
218
# Standard development setup
219
xo --fix --space 2 --react
220

221
# Pre-commit hook setup
222
xo --quiet --reporter=compact
223

224
# CI/CD pipeline
225
xo --reporter=junit --quiet
226

227
# Debug configuration
228
xo --print-config=src/index.ts
229
```
230

231
### Advanced Usage
232

233
```bash
234
# Custom ignore patterns for build artifacts
235
xo --ignore "dist/**" --ignore "build/**" --ignore "*.generated.*"
236

237
# TypeScript project with custom config
238
xo --config ./tsconfig.eslint.json --cwd ./src "**/*.{ts,tsx}"
239

240
# Multi-project monorepo
241
xo --cwd ./packages/frontend --react --prettier
242
xo --cwd ./packages/backend --space 4
243
```
244

245
### Integration Examples
246

247
```bash
248
# Package.json script
249
"scripts": {
250
  "lint": "xo",
251
  "lint:fix": "xo --fix",
252
  "lint:ci": "xo --quiet --reporter=junit"
253
}
254

255
# Git pre-commit hook
256
#!/bin/sh
257
xo --fix --quiet && git add .
258

259
# VS Code task
260
{
261
  "type": "shell",
262
  "command": "xo",
263
  "args": ["--fix", "--open"],
264
  "group": "build"
265
}
266
```
267

268
## Error Handling
269

270
XO provides clear error messages and suggestions:
271

272
```bash
273
# Configuration errors
274
$ xo --print-config=""
275
Error: The `--print-config` flag must be used with exactly one filename
276

277
# Invalid options
278
$ xo --invalid-option
279
Error: Unknown option: --invalid-option
280

281
# File access errors
282
$ xo --config ./missing-config.js
283
Error: Config file not found: ./missing-config.js
284
```
285

286
## Environment Variables
287

288
XO respects certain environment variables:
289

290
```bash
291
# GitHub Actions integration (automatically enables quiet mode)
292
GITHUB_ACTIONS=true xo
293

294
# Node.js options
295
NODE_OPTIONS="--max-old-space-size=8192" xo large-project/
296
```
297

298
## Reporter Options
299

300
XO supports multiple built-in reporters:
301

302
- `stylish` (default): Human-readable format with colors
303
- `compact`: Compact format for CI environments  
304
- `json`: Machine-readable JSON output
305
- `junit`: JUnit XML format for CI integration
306
- `checkstyle`: Checkstyle XML format
307
- `tap`: TAP (Test Anything Protocol) format
308
- `unix`: Unix-style format
309

310
```bash
311
# Examples of different reporters
312
xo --reporter=json > lint-results.json
313
xo --reporter=junit > junit-results.xml
314
xo --reporter=compact --quiet
315
```