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package main
import (
"bufio"
"flag"
"fmt"
"os"
"strconv"
"strings"
"time"
)
type Iface struct {
Name string
RxBytes uint64
RxPackets uint64
RxErrs uint64
TxBytes uint64
TxPackets uint64
TxErrs uint64
}
// human readable bits 'n bytes per second
// assumes bytes input.
func humanBps(bps float64, raw bool, bits bool) string {
prefixes := []string{"", "k", "M", "G", "T", "P", "E", "Z", "Y"}
unit := "B/s"
if bits {
bps *= 8
unit = "b/s"
}
if raw {
return fmt.Sprintf("%.2f", bps)
}
prefix := 0
for prefix+1 < len(prefixes) && bps >= 1000 {
bps /= 1000
prefix++
}
return fmt.Sprintf("%.2f %s%s", bps, prefixes[prefix], unit)
}
func main() {
bitFlag := flag.Bool("b", false, "render bits not bytes")
intervalFlag := flag.String("d", "1s", "update interval (e.g. 500ms, 1s, 2s)")
pathFlag := flag.String("f", "/proc/net/dev", "path")
interfaceFlag := flag.String("i", "", "interface to report on")
rawFlag := flag.Bool("r", false, "show raw values, not human")
versionFlag := flag.Bool("V", false, "show version information")
flag.Parse()
if *versionFlag {
fmt.Println("fsbm-go version 1.0")
os.Exit(0)
}
interval, err := time.ParseDuration(*intervalFlag)
if err != nil {
fmt.Fprintf(os.Stderr, "invalid duration (%s): %v", *intervalFlag, err)
os.Exit(1)
}
if _, err := os.Stat(*pathFlag); err != nil {
fmt.Fprintf(os.Stderr, "cannot access %s: %v\n", *pathFlag, err)
os.Exit(1)
}
limitIfaces := false
requestedIfaces := make(map[string]struct{})
if *interfaceFlag != "" {
for _, name := range strings.Split(*interfaceFlag, ",") {
requestedIfaces[name] = struct{}{}
}
if len(requestedIfaces) > 0 {
limitIfaces = true
}
}
ifaces := make(map[string]Iface)
var prevTime time.Time
for {
openTime := time.Now()
file, err := os.Open(*pathFlag) // For read access.
if err != nil {
fmt.Fprintf(os.Stderr, "cannot access %s: %v\n", *pathFlag, err)
os.Exit(1)
}
scanner := bufio.NewScanner(file)
for scanner.Scan() {
line := strings.TrimSpace(scanner.Text())
name, rest, found := strings.Cut(line, ":")
if !found {
continue
}
if limitIfaces {
_, ok := requestedIfaces[name]
if !ok {
continue
}
}
fields := strings.Fields(rest)
if len(fields) != 16 {
fmt.Fprintf(os.Stderr, "cannot parse %s", line)
os.Exit(1)
}
cur := Iface{
Name: name,
}
cur.RxBytes, _ = strconv.ParseUint(fields[0], 10, 64) // RxBytes uint64
cur.RxPackets, _ = strconv.ParseUint(fields[1], 10, 64) // RxPackets uint64
cur.RxErrs, _ = strconv.ParseUint(fields[2], 10, 64) // RxErrs uint64
cur.TxBytes, _ = strconv.ParseUint(fields[8], 10, 64) // TxBytes uint64
cur.TxPackets, _ = strconv.ParseUint(fields[9], 10, 64) // TxPackets uint64
cur.TxErrs, _ = strconv.ParseUint(fields[10], 10, 64) // TxErrs uint64
prev, exists := ifaces[name]
if exists {
// deltas
timeDiff := openTime.Sub(prevTime).Seconds()
rxRate := float64(cur.RxBytes-prev.RxBytes) / timeDiff
txRate := float64(cur.TxBytes-prev.TxBytes) / timeDiff
fmt.Printf("%s: (%s, %s) ", name, humanBps(rxRate, *rawFlag, *bitFlag), humanBps(txRate, *rawFlag, *bitFlag))
}
ifaces[name] = cur
}
fmt.Printf("\n")
file.Close()
prevTime = openTime
time.Sleep(interval)
}
}
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