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對於一個類，我需要在C中創建我自己的shell。 我正在嘗試使用管道支持命令的管道。據我可以告訴管道的兩端關閉。儘管如此，我沒有得到任何結果，任何人都可以發現這裏有什麼問題嗎？在c中支撐殼體的管道
do_ *函數帶有一個小錯誤處理包裝函數。爲了完整起見，它們包含在頁面的底部。
該函數產生一個程序並確保孩子只能讀寫正確的管道。
int execute_piped_binairy (int input, int output, Pgm *program){
pid_t pid = do_fork();
if (pid == 0){ //I am the child
if (input != 0){//input is not standard input, overwrite stdin with given input
do_dub_and_close(input, 0);
} if (output != 1) { //output is not standard output, overwrite stdout with given output
do_dub_and_close(output, 1);
}
do_exec(program->pgmlist);
} else {
return pid;
}
}
該函數產生k個孩子和k-1管道以執行k個命令。命令以相反的順序給出，這意味着第一個命令應該輸出到全局輸出。
int execute_binairy_list (int input, int output, int pgmCount, Pgm *program){
int childPids[pgmCount];
int childStatus[pgmCount];
int childId;
int idx;
// For k programs we need k-1 pipes and need to spawn k children
for(idx = 0; idx<pgmCount-1; idx++){
int file_descriptors[2]={0, 1};
//create unnamed pipe
do_pipe(file_descriptors);
// pass stored input and created write file descriptor
childId = do_execute_piped_binairy (file_descriptors[0], output, program+idx);
childPids[idx]=childId; //keep child id to make parent wait for all children.
if(output!=1){
do_close(output);
};
do_close(file_descriptors[0]); // close read end of new pipe, child reads from this pipe.
output = file_descriptors [1]; //store write end of new pipe for next iteration
}
//we still need to spawn 1 child to execute the first command based on the global input
// pass stored input and created write file descriptor
childId = do_execute_piped_binairy (input, output, program+idx);
childPids[idx]=childId; //keep child id to make parent wait for all children.
if(output!=1){
do_close(output);
};
for(idx=0; idx<pgmCount; idx++){
do_wait(childPids[idx], childStatus+idx); //wait for all children to return;
}
return 0;
}
我測試了我的三個命令心願的代碼會導致這個順序： 命令1 - > PIPE1 - >命令2 - > pipe2 - >命令3 當有很多printfs輸出的運行，這是發生了什麼（更或更小的調度影響的順序排列）：
created pipe: 3 4 //pipe 2
created child: 2452 //command 3
closed input: 3 //parent closes read end of pipe 2
created pipe: 3 5 //pipe 1
child: 2452 3 1 //command 3 reads from read end of pipe 2 and writes to 1
closed input: 3 2452 //command 3 closes read end of pipe 2
created child: 2453 //command 2
closed output: 4 //parent closes write end of pipe 2
closed input: 3 //parent closes read end of pipe 1
closed output: 5 //parent closes write end of pipe 1
child: 2453 3 4 //command 2 reads from read end of pipe 1 and writes to write end of pipe 2
closed input: 3 2453 //command 2 closes read end of pipe 1
closed output: 4 2453 //command 2 closes write end of pipe 2
child: 2454 0 5 //command 1 reads from 0 and writes to write end of pipe 1
closed output: 5 2454 //command 1 closes write end of pipe 1
任何幫助感激