如何解决错误的文件描述符和我的文件输出被锁定我无法访问我的代码创建的文件
所以我在将终端命令输出输出到文件时遇到了问题。我的任务是创建一个程序，该程序对给定文本文件中的每个命令使用 fork，并使用 execvp() 运行所述命令。在我的代码（特别是我在代码中注释的子进程）中，我使用 open() 创建文件并使用 dup2() 将命令行输出输出到文件中。我的问题是出现错误：“写入错误：文件描述符错误。”我用来测试我的程序的文件包含以下 shell 命令
sleep 5
ls -latr
sleep 3
pwd
sleep 1
wc /etc/passwd
该程序对 sleep 命令运行良好，但对其他命令不起作用。该程序还会创建一个我无法访问的 .out 文件。
Here is a picture of the files I can't access
Here is a screenshot of the output if I run the program in my terminal
这是我的代码：
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <string.h>
int main(int argc,char *argv[])
{
FILE* myfile = fopen(argv[1],"r"); //opens file
if(myfile == NULL)
{
printf("Error file is null");
}
//separate each line of the file into a command
char commands[100][1000]; //Contains the commands of the file. Max array of size of 100 commands and 1000 chars per command
char line [128];
int i = 0; //iterator,counts total amount of lines/commands
while (fgets(line,sizeof line,myfile) != NULL) /* read a line */
{
strcpy(commands[i],line); /* write the line */
i++;
}
//Parse commands to be readable by execvp by using strtok
char *arguments[100][(1000/2)+1]; //max of 501 arguments,will be used for execvp()
for(int k = 0; k < i; k++)
{
commands[k][strlen(commands[k])-1] = '\0';
arguments[k][0] = strtok(commands[k]," ");
int l = 0; //iterator
while(arguments[k][l] != NULL)
{
arguments[k][++l] = strtok(NULL," ");
}
}
pid_t pids[i]; //create process pid array of size [total commands in the file]
//for loop runs i amount of times,i == total commands
for(int j = 0; j < i; j++)
{
pids[j] = fork();
//If fork fails,exit
if((pids[j] < 0))
{
printf("An error occured creating the fork \n");
return 2;
}
//This is the Child Processes
else if(pids[j] == 0)
{
if(myfile == NULL)
{
printf("\n Error! File is NULL... \n");
}
else
{
char outBuffer[50];
char errBuffer[50];
pid_t childPID = getpid();
pid_t parentPID = getppid();
sprintf(outBuffer,"%d.out",childPID);
sprintf(errBuffer,"%d.err",parentPID);
int outFile = open(outBuffer,O_RDWR | O_CREAT | O_APPEND | 0777);
int errFile = open(errBuffer,O_RDWR | O_CREAT | O_APPEND | 0777);
if (outFile < 0 || errFile < 0)
{
printf("Error with opening the out/err file");
}
dup2(outFile,1);
dup2(errFile,2);
close(errFile);
close(outFile);
printf("Starting command %d: child %d pid of parent %d \n",j+1,childPID,parentPID);
int err = execvp(arguments[j][0],arguments[j]);
if(err == -1)
{
printf("Could not find the given program to execute \n");
return 2;
}
printf("Finished child %d pid of parent %d \n",parentPID);
}
}
}
fclose(myfile);
//This is the parent process
for(int j = 0; j < i; j++)
{
int wstatus;
wait(&wstatus);
if(WIFEXITED(wstatus))
{
int statusCode = WEXITSTATUS(wstatus);
if(statusCode == 0)
{
printf("Successful execution! \n");
}
else
{
printf("Exited with exit code: %d \n",statusCode);
}
}
}
return 0;
}
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