hnakra/cli/cli.go

// Package cli provides utilities for writing command line utilities that
// interact with services.
package cli

import "os"
import "fmt"
import "flag"
import "strings"

// Sayf is like Printf, but prints the program name before the message. This is
// used for printing messages and errors.
func Sayf (format string, values ...any) {
	Printf(os.Args[0] + ": " + format, values...)
}

// Printf prints to stderr.
func Printf (format string, values ...any) {
	fmt.Fprintf(flag.CommandLine.Output(), format, values...)
}

// ServiceUser returns the system user that corresponds to the given service
// name. This is not necissarily equivalent Hnakra user, although it is good
// practice to have a 1:1 correspondance between them.
func ServiceUser (service string) string {
	return "hn-" + strings.ToLower(service)
}

// NeedRoot halts the program and displays an error if it is not being run as
// root. This should be called whenever an operation takes place that requires
// root privelages.
func NeedRoot() {
	uid := os.Getuid()
	if uid != 0 {
		Sayf("this utility must be run as root")
		os.Exit(1)
	}
}