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我正在做一個代碼，它將執行Linux命令管道。基本上在我的代碼中，它將解析用戶輸入命令，然後使用execvp函數運行它。爲什麼我的C++數組打印相同的值？
但是，要做到這一點，我需要知道命令以及它的參數。我一直試圖讓解析工作正常，但是，似乎當我做一個測試用例時，來自兩個存儲它們各自程序的數組的輸出是相同的。命令/參數存儲在名爲prgname1和prgname2的字符數組中。例如，如果我用參數「ps aux | grep [username]」運行我的程序，則prgname1 [0]和prgname2 [0]的輸出都是[用戶名]。它們分別應該是ps和grep。
任何人都可以看看我的代碼，看看我可能有哪個錯誤導致這個？
謝謝！
#include <sys/wait.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <iostream>
#define MAX_PARA_NUM 5
#define MAX_COMMAND_LEN 1024
using namespace std;
int main(int argc, char *argv[]) {
char *prgname1[MAX_PARA_NUM], *prgname2[MAX_PARA_NUM];
char command[MAX_COMMAND_LEN];
int pfd[2];
pipe(pfd);
pid_t cid1, cid2;
char *full = argv[1];
char str[MAX_COMMAND_LEN];
int i = 0;
int j = 0;
int k = 0;
int ind = 0;
while (ind < strlen(full)) {
if (full[ind] == ' ') {
strncpy(command, str, i);
cout << command << endl;
prgname1[j] = command;
j++;
i = 0;
ind++;
}
else {
str[i] = full[ind];
i++;
ind++;
}
if(full[ind] == '|') {
i = 0;
j = 0;
ind+=2;
while (ind < strlen(full)) {
if (full[ind] == ' ') {
strncpy(command, str, i);
cout << command << endl;
prgname2[j] = command;
j++;
i = 0;
ind++;
}
else {
str[i] = full[ind];
i++;
ind++;
}
if (ind == strlen(full)) {
strncpy(command, str, i);
cout << command << endl;
prgname2[j] = command;
break;
}
}
}
}
// test output here not working correctly
cout << prgname1[0] << endl;
cout << prgname2[0] << endl;
// exits if no parameters passed
if (argc != 2) {
cout << "Usage:" << argv[0] << endl;
exit(EXIT_FAILURE);
}
// exits if there is a pipe error
if (pipe(pfd) == -1) {
cerr << "pipe" << endl;
exit(EXIT_FAILURE);
}
cid1 = fork(); // creates child process 1
// exits if there is a fork error
if (cid1 == -1 || cid2 == -1) {
cerr << "fork";
exit(EXIT_FAILURE);
}
// 1st child process executes and writes to the pipe
if (cid1 == 0) {
char **p = prgname1;
close(1); // closes stdout
dup(pfd[1]); // connects pipe output to stdout
close(pfd[0]); // closes pipe input as it is not needed
close(pfd[1]); // closes pipe output as pipe is connected
execvp(prgname1[0], p);
cerr << "execlp 1 failed" << endl;
cid2 = fork();
}
// 2nd child process reads from the pipe and executes
else if (cid2 == 0) {
char **p = prgname2;
close(0); // closes stdin
dup(pfd[0]); // connects pipe input to stdin
close(pfd[0]); // closes pipe input as pipe is connected
close(pfd[1]); // closes pipe output as it is not needed
execvp(prgname2[0], p);
cerr << "execlp 2 failed" << endl;
}
else {
sleep(1);
waitpid(cid1, NULL, 0);
waitpid(cid2, NULL, 0);
cout << "Program successfully completed" << endl;
exit(EXIT_SUCCESS);
}
return 0;
}