如何在Shell脚本中处理Ctrl + c？

问题描述

我正在尝试在shell脚本中处理ctrl + c。我在while循环中运行代码，但是我从脚本中调用二进制文件并在后台运行它，因此当我要停止二进制文件时应该停止。代码在hello.c下面
vim hello.c

#include <stdio.h>

int main()
{
while(1)
{
int n1,n2;
printf("Enter the first number\n");
scanf("%d",&n1);
printf("Enter the second number\n");
scanf("%d",&n2);
printf("Entered number are n1 = %d,n2 =%d\n",n1,n2);


}
}

下面是我使用的Bash脚本。

#/i/bin/sh
echo run the hello binary
./hello < in.txt &


trap_ctrlc()
{
        ps -eaf | grep hello | grep -v grep | awk  '{print $2}' | xargs kill -9
        echo trap_ctrlc
        exit
}

trap trap_ctrlc SIGHUP SIGINT SIGTERM

启动脚本后，hello二进制文件将连续运行。我已经使用kill -9 pid命令从其他终端杀死了此二进制文件。
我已经尝试过这个trap_ctrlc函数，但是它不起作用。如何在Shell脚本中处理Ctrl + c。在in.txt中，我添加了输入，因此我可以将此文件直接传递给二进制文件
vim in.txt

1
2

输出：
输入第一个号码
输入第二个数字
输入的数字为n1 = 1，n2 = 2
输入第一个号码
输入第二个数字
输入的数字为n1 = 1，n2 = 2
输入第一个号码
输入第二个数字
输入的数字为n1 = 1，n2 = 2
并且持续不断。

解决方法

更改您的c程序，以便它检查读取数据是否真的成功：

#include <stdio.h>

int main()
{
    int n1,n2;
    while(1) {
        printf("Enter the first number\n");
        if(scanf("%d",&n1) != 1) return 0;   /* check here */
        printf("Enter the second number\n");
        if(scanf("%d",&n2) != 1) return 0;   /* check here */
        printf("Entered number are n1 = %d,n2 =%d\n",n1,n2);
    }
}

当in.txt的输入耗尽时，它将终止。

要制作可以从in.txt读取很多次的内容，您可以在bash脚本中创建一个循环，该循环可以永远为./hello供电（或直到被杀死）。

示例：

#!/bin/bash

# a function to repeatedly print the content in "in.txt"
function print_forever() {
    while [ 1 ];
    do
        cat "$1"
        sleep 1
    done
}

echo run the hello binary
print_forever in.txt | ./hello &
pid=$!
echo "background process $pid started"

trap_ctrlc() {
    kill $pid
    echo -e "\nkill=$? (0 = success)\n"
    wait $pid
    echo "wait=$? (the exit status from the background process)"
    echo -e "\n\ntrap_ctrlc\n\n"
}

trap trap_ctrlc INT

# wait for all background processes to terminate
wait

可能的输出：

$ ./hello.sh
run the hello binary
background process 262717 started
Enter the first number
Enter the second number
Entered number are n1 = 1,n2 =2
Enter the first number
Enter the second number
Entered number are n1 = 1,n2 =2
Enter the first number
^C
kill=0 (0 = success)

wait=143 (the exit status from the background process)


trap_ctrlc

另一种选择是杀死wait后杀死孩子：

#!/bin/bash

function print_forever() {
    while [ 1 ];
    do
        cat "$1"
        sleep 1
    done
}
 
echo run the hello binary
print_forever in.txt | ./hello &
pid=$!
echo "background process $pid started"
 
trap_ctrlc() {
    echo -e "\n\ntrap_ctrlc\n\n"
}
 
trap trap_ctrlc INT
 
# wait for all background processes to terminate
wait
echo first wait=$?
kill $pid
echo -e "\nkill=$? (0 = success)\n"
wait $pid
echo "wait=$? (the exit status from the background process)"`
``

bash sigint