BASH腳本中的多線程ping

Question

我在這裏和周圍看了一下，似乎只提出了一個關於BASH環境中ping多線程的問題。

代碼

data=$(<~/Desktop/hosts.txt) 
    for line in $data 
    do 
     ping -c1 $line &> /dev/null & 
     echo $line is reachable || 
     echo $line is down 
    done 

的問題是，當實際上只有3個的/ 24是到達其循環通過文件，並報告所有的IP內的IP地址範圍的地址作爲可達.. 。

我已經嘗試通過增加-W 1對ping減慢掃描，但這會導致性能不合格，並需要使用多線程

Answer 1

作爲編碼的你有2個獨立的，不相關的命令：

# run `ping` and place in background 
ping -c1 $line & 

和

# regardless of what the `ping` command does ... always 
# print 'reachable` and if that fails print `down` 
echo $line is reachable || echo $line is down 

我假設你真正想要的是使用ping（成功或失敗）的結果，以確定哪些echo命令發佈;在這種情況下，你需要用雙`& &「像這樣的替代單&：

ping -c1 $line && 
echo $line is reachable || 
echo $line is down 

雖然這應該提供條件的輸出，你坪現在在前臺執行一個-AT-A-時間。

如果你想在後臺運行的坪（即「多線程」）和也執行條件打印，你可以放置ping/echo/echo代碼的函數裏面，然後在for循環做出了一個電話功能......確保放置在後臺的函數調用，如：

網站

樣本列表要平：

$ cat pinglist 
www.yahoo.com 
www.google.com 
www.peanut_butter.and_jelly 
www.bbc.co.uk 
www.not_today_your.not 

建議腳本：

$ cat pinger 
#!/bin/bash 
function pingit() { 

    target=${1} 

    # send stdout/stderr to /dev/null since all we need is the return code 

    ping -c1 ${target} >/dev/null 2>&1 && 
    echo ${target} is reachable || 
    echo ${target} is down 
} 

data=$(<pinglist) 

for line in ${data} 
do 
    # call our function and place the call in the background 

    pingit ${line} & 
done 

# wait for all outstanding background jobs to complete before continuing 

wait 

# [optional] let operator know we're done. 
echo "Completed." 

點

一些樣品運行，同時要注意的是，輸出消息的順序會根據每個ping命令完成的速度有多快：

$ pinger 
www.yahoo.com is reachable 
www.google.com is reachable 
www.peanut_butter.and_jelly is down 
www.bbc.co.uk is reachable 
www.not_today_your.not is down 
Completed. 

$ pinger 
www.peanut_butter.and_jelly is down 
www.not_today_your.not is down 
www.google.com is reachable 
www.bbc.co.uk is reachable 
www.yahoo.com is reachable 
Completed. 

我們將再次運行測試和排序輸出，忽略「已完成」。消息：

$ pinger | egrep -v "Completed" | sort 
www.bbc.co.uk is reachable 
www.google.com is reachable 
www.not_today_your.not is down 
www.peanut_butter.and_jelly is down 
www.yahoo.com is reachable 

---

！請記住，如果你有一長串主機可以ping通，並且你在一個小小的盒子上運行這個腳本，那麼如果你啓動數以千計的同時撥打的數千個電話，那麼你的系統管理員可能不會太高興......並且天堂禁止你犯一個編碼錯誤，產生一個無限循環的命令。

這種類型的不端行爲可以被編碼爲（例如，限制未ping來電或sleep荷蘭國際集團爲ping電話等每一個X號後幾秒鐘的數量），但我會離開這個編碼功課;-)

---

如果你不想用的功能（例如，你正在做一個快速的命令行中環/平）來打擾，你可以包裝在括號中ping/echo/echo並運行此結構在背景，雖然你會想要決定如何處理與工作有關的信息，例如：

$ data=$(<pinglist) 
$ for line in ${data} 
do 
    (ping -c1 ${line} >/dev/null 2>&1 && echo ${line} is reachable || echo ${line} is down) & 
done 
[1]  12212 
[2]  12213 
[3]  12214 
[4]  12215 
[5]  12217 
www.google.com is reachable 
www.peanut_butter.and_jelly is down 
www.not_today_your.not is down 
www.bbc.co.uk is reachable 
www.yahoo.com is reachable 
[5] + Done     for line in ${data};do; (ping -c1 ${line} >/dev/null 2>&1 && echo ${line} is reachable || echo ${line} is down) & 2>/dev/null;done 
[4] - Done     for line in ${data};do; (ping -c1 ${line} >/dev/null 2>&1 && echo ${line} is reachable || echo ${line} is down) & 2>/dev/null;done 
[3] Done     for line in ${data};do; (ping -c1 ${line} >/dev/null 2>&1 && echo ${line} is reachable || echo ${line} is down) & 2>/dev/null;done 
[2] Done     for line in ${data};do; (ping -c1 ${line} >/dev/null 2>&1 && echo ${line} is reachable || echo ${line} is down) & 2>/dev/null;done 
[1] Done     for line in ${data};do; (ping -c1 ${line} >/dev/null 2>&1 && echo ${line} is reachable || echo ${line} is down) & 2>/dev/null;done 

一個選項（組裝機？），用於掩蓋工作相關的消息需要包裝我們ping/echo/echo/&中包含的語句和指導標準錯誤到/ dev/null的...

$ data=$(<pinglist) 
$ for line in ${data} 
do 
    {(ping -c1 ${line} >/dev/null 2>&1 && echo ${line} is reachable || echo ${line} is down) & } 2>/dev/null 
done 
www.peanut_butter.and_jelly is down 
www.not_today_your.not is down 
www.google.com is reachable 
www.yahoo.com is reachable 
www.bbc.co.uk is reachable 

...雖然這可能掩蓋一些你可能感興趣的錯誤信息，ymmv。

Answer 2

我先給GNU並行做一次他們都在平行對我來說，可能是32：

parallel -j 32 -a hosts.txt 'ping -c1 {} > /dev/null 2>&1 && echo {} is available || echo {} is down'