Command-line arguments and flags

The os.Args variable holds the command-line arguments – starting with the program name – which are passed to a Go program.

func main() {
	if len(os.Args) != 3 {
		fmt.Println("Usage:", os.Args[0], "PATTERN", "FILE")
		return
	}
	pattern := os.Args[1]
	file := os.Args[2]
	// ...
}

$ go build grep.go
$ ./grep
Usage: ./grep PATTERN FILE

Flag parsing

The flag package implements basic command-line flag parsing.

More code examples

Go blueprints: code for com­mon tasks is a collection of handy code examples.

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