output.go

package main

import (
	"fmt"
	"log"
	"os"
	"strings"
)

func PrintKeys(outputPath *string, keys map[string][]string) {
	fd := os.Stdout

	// Open output file if necessary
	if outputPath != nil {
		var err error
		fd, err = os.OpenFile(*outputPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
		if err != nil {
			log.Fatal(fmt.Sprintf("Failed to open %s\n", *outputPath))
		}
		defer fd.Close()
	}

	// header, written once
	fmt.Fprintf(fd, "\n########################################################\n")
	fmt.Fprintf(fd, "# Generated by https://github.com/samber/sync-ssh-keys #\n")
	fmt.Fprintf(fd, "########################################################\n\n")

	for s, sshKeys := range keys {
		if len(keys) > 0 {
			fmt.Fprintf(fd, "#\n# %s\n#\n\n%s\n", s, strings.Join(sshKeys, "\n\n"))
		}
	}

	fmt.Fprintf(fd, "\n# END\n")
}