A simple concurrent go program to clear out (log)files.

logmuncher.go

package main

import (
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path/filepath"
	"sync"
	"time"
)

var (
	// This will be set once (controlled via. command line flags) in the main function
	// then never modified again. Thus multiple concurrent readers are allowed.
	Mock = false

	// This will be set once (controlled via. command line flags) in the main function
	// then never modified again.
	RemovalThreshold = 7
)

func shouldBeRemoved(dirent os.FileInfo) bool {
	if int(time.Since(dirent.ModTime()).Hours()) > (RemovalThreshold * 24) {
		return true
	}
	return false
}

func remove(dirname string, dirent os.FileInfo, wg *sync.WaitGroup) {
	dirpath := filepath.Join(dirname, dirent.Name())
	if Mock {
		fmt.Println(dirpath)
	} else {
		err := os.Remove(dirpath)
		if err != nil {
			if os.IsPermission(err) {
				fmt.Printf("Could not remove %s due to insufficient permissions.\n", dirpath)
			} else {
				log.Println(err)
			}
		} else {
			fmt.Printf("Removed %s\n", dirpath)
		}
	}
	wg.Done()
}

func clearLogDir(dirname string, wg *sync.WaitGroup) {
	dirents, err := ioutil.ReadDir(dirname)
	if err != nil {
		log.Println(err)
		wg.Done()
		return
	}

	for _, dirent := range dirents {
		if dirent.IsDir() {
			// Recursively walk all subdirectories (in a concurrent manner).
			wg.Add(1)
			go clearLogDir(filepath.Join(dirname, dirent.Name()), wg)
		} else if shouldBeRemoved(dirent) {
			// Remove the file. Use another goroutine since file removal will require a syscall.
			wg.Add(1)
			go remove(dirname, dirent, wg)
		}
	}

	wg.Done()
}

func main() {
	flag.BoolVar(&Mock, "mock", Mock, "Set this flag if you want to perform a dry/mock run.")
	flag.IntVar(&RemovalThreshold, "days", RemovalThreshold, "The minimum age of a file relative to now for it to be deleted.")
	flag.Parse()

	var wg sync.WaitGroup

	wg.Add(1)
	go clearLogDir("/var/log/", &wg)

	wg.Wait()
}