bash的陷阱中断命令，但应退出环路结束 [英] bash trap interrupt command but should exit on end of loop

问题描述

从来就问猛砸陷阱 - 出口仅在循环的结束和提交解决方案的工作，但同时pressing CTRL-C在脚本运行命令（mp3convert与跛脚）将被打断，比完整的循环将运行到最后。让我告诉你这个简单的脚本：

I´ve asked Bash trap - exit only at the end of loop and the submitted solution works but while pressing CTRL-C the running command in the script (mp3convert with lame) will be interrupt and than the complete for loop will running to the end. Let me show you the simple script:

#!/bin/bash
mp3convert () { lame -V0 file.wav file.mp3 }

PreTrap() { QUIT=1 }

CleanUp() {
  if [ ! -z $QUIT ]; then
     rm -f $TMPFILE1
     rm -f $TMPFILE2
     echo "... done!" && exit
  fi }

trap PreTrap SIGINT SIGTERM SIGTSTP
trap CleanUp EXIT

case $1 in
     write)
           while [ -n "$line" ]
             do
                mp3convert
                [SOMEMOREMAGIC]
                CleanUp
             done
    ;;
QUIT=1

如果我preSS CTRL-C，而功能mp3convert运行瘸腿命令将被打断，然后清理运行之前[SOMEMOREMAGIC]会执行。我不明白为什么跛脚命令将被打断，我怎么能避免它们。

If I press CTRL-C while function mp3convert is running the lame command will be interrupt and then [SOMEMOREMAGIC] will execute before CleanUp is running. I don´t understand why the lame command will be interrupt and how I could avoid them.

推荐答案

尝试简化上面的讨论，我包下图显示案例脚本更容易理解的版本。该脚本还处理了双控-C的问题：
（双控-C的问题：如果你打控制c两次或者三次，这取决于有多少等待$ PID 你使用，这些清理不能正常进行。 ）

Try to simplify the discussion above, I wrap up an easier understandable version of show-case script below. This script also HANDLES the "double control-C problem": (Double control-C problem: If you hit control C twice, or three times, depending on how many wait $PID you used, those clean up can not be done properly.)

#!/bin/bash

mp3convert () {
  echo "mp3convert..."; sleep 5; echo "mp3convert done..."
}

PreTrap() {
  echo "in trap"
  QUIT=1
  echo "exiting trap..."
}

CleanUp() {
  ### Since 'wait $PID' can be interrupted by ^C, we need to protected it
  ### by the 'kill' loop  ==> double/triple control-C problem.
  while kill -0 $PID >& /dev/null; do wait $PID; echo "check again"; done

  ### This won't work (A simple wait $PID is vulnerable to double control C)
  # wait $PID

  if [ ! -z $QUIT ]; then
     echo "clean up..."
     exit
 fi
}

trap PreTrap SIGINT SIGTERM SIGTSTP
#trap CleanUp EXIT

for loop in 1 2 3; do
    (
      echo "loop #$loop"
      mp3convert
      echo magic 1
      echo magic 2
      echo magic 3
    ) &
    PID=$!
    CleanUp
    echo "done loop #$loop"
done

的杀-0 招可以在此链接

这篇关于bash的陷阱中断命令，但应退出环路结束的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！