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我正在尝试将表达式从主要传递给3个孩子。 每个孩子修改表达式，并且在第三个孩子完成后，表达式返回到main，并打印在屏幕上。儿童叉后无法正常工作
我已经运行每个孩子自己，似乎工作得很好。 但是，当我尝试在主要execlp东西出错了。
每个孩子在文件（频道）填充数据后读取，然后删除频道的内容。
int main(int argc, char* argv[]){
char expr_buffer[MAX_CHAR + 1];
int rmv,i;
int fd1,fd2,fd3,fd4, expr_len, sync;
ssize_t bytes_written, bytes_read;
off_t offset;
do{
fd1 = open("Channel_1.txt", O_RDWR | O_CREAT, NULL);
if (fd1 < 0){
perror("Error opening \"Channel_1.txt\".\n");
return(1);
}
fd2 = open("Channel_2.txt", O_RDWR | O_CREAT, NULL);
if (fd2 < 0){
perror("Error opening \"Channel_2.txt\".\n");
return(1);
}
fd3 = open("Channel_3.txt", O_RDWR | O_CREAT, NULL);
if (fd3 < 0){
perror("Error opening \"Channel_3.txt\".\n");
return(1);
}
fd4 = open("Channel_4.txt", O_RDWR | O_CREAT, NULL);
if (fd4 < 0){
perror("Error opening \"Channel_4.txt\".\n");
return(1);
}
char formatstring[13];
printf("Waiting for expression...\n");
sprintf(formatstring,"%%%ds",MAX_CHAR);
scanf(formatstring, expr_buffer);
for(i=0; i<MAX_CHAR + 1; i++){
if ((expr_buffer[i] == '\0') && (i != MAX_CHAR)){
expr_buffer[i] ='\n';
expr_buffer[i+1] = '\0';
break;
}
else if((expr_buffer[i] == '\0') && (i == MAX_CHAR)){
expr_buffer[i-1]= '\n';
break;
}
}
expr_len = strlen(expr_buffer);
struct stat file_stat;
off_t file_size;
int pid_1, pid_2, pid_3;
int status_1, status_2, status_3;
if (ftruncate(fd1, (off_t)0) == -1){
perror("Error erasing content of file: \"Channel_1.txt\".\n");
return -1;
}
bytes_written = write(fd1, expr_buffer, expr_len*sizeof(char));
if (bytes_written < 0) {
perror("Error writing to file: \"Channel_1.txt\"");
if (close(fd1) < 0) {
perror(NULL);
}
return 1;
}
if (bytes_written < expr_len) {
printf("Incomplete data written to file: \"Channel_1.txt\".\n");
}
sync = fsync(fd1);
if (sync == 0){
printf("Data written successfully to file: \"Channel_1.txt\".\n");
}
else {
perror("Error syncing data to disk.\n");
return(-2);//
}
if (!(pid_1 = fork())) {
printf("trying to execute Child_1\n");
execlp("./Child_1","Channel_1.txt","Channel_2.txt", NULL);
perror("execlp");
return(1);
}
waitpid(pid_1,&status_1,0);
if (WIFEXITED(status_1)) {
printf("child returned %d\n", WEXITSTATUS(status_1));
}
else {
printf("child_1 terminated abnormally\n");
}
if (!(pid_2=fork())) {
printf("trying to execute Child_2\n");
execlp("./Child_2", "Channel_2.txt","Channel_3.txt", NULL);
perror("execlp");
return(1);
}
waitpid(pid_2,&status_2,0);
if (WIFEXITED(status_2)) {
printf("child returned %d\n", WEXITSTATUS(status_2));
}
else {
printf("child_2 terminated abnormally\n");
}
if (!(pid_3 = fork())) {
printf("trying to execute Child_3\n");
execlp("./Child_3", "Channel_3.txt","Channel_4.txt",NULL);
perror("execlp");
return(1);
}
waitpid(pid_3,&status_3,0);
if (WIFEXITED(status_3)) {
printf("child returned %d\n", WEXITSTATUS(status_3));
}
else {
printf("child_3 terminated abnormally\n");
}
while(1){
if (fstat(fd4, &file_stat) == -1) {
perror("Fstat.");
return(-1);
}
file_size = file_stat.st_size;
if (file_size == 0){
printf("\"Channel_4.txt\" is empty.\n");
}
else{
break;
}
}
bytes_read = read(fd4, expr_buffer, MAX_CHAR*sizeof(char));
if (bytes_read < 0) {
perror("Read failure for file: \"Channel_4.txt\"\n");
close(fd1);
return 1;
}
printf("%s\n",expr_buffer);
if (close(fd1) < 0) {
perror(NULL);
return 2;//
}
if (close(fd2) < 0) {
perror(NULL);
return 2;//
}
if (close(fd3) < 0) {
perror(NULL);
return 2;//
}
if (close(fd4) < 0) {
perror(NULL);
return 2;//
}
}while(expr_buffer[0] != 'q');
rmv = remove("Channel_1.txt");
if (rmv == -1){
perror("Error removing Channel_1.txt.\n");
}
rmv = remove("Channel_2.txt");
if (rmv == -1){
perror("Error removing Channel_2.txt.\n");
}
rmv = remove("Channel_3.txt");
if (rmv == -1){
perror("Error removing Channel_3.txt.\n");
}
rmv = remove("Channel_4.txt");
if (rmv == -1){
perror("Error removing Channel_4.txt.\n");
}
return(0);
}
而这child_1的一部分
int main(int argc, char *argv[]){
int expr_len;
int fd5,fd2,i,j,k;
off_t offset;
int bytes_read,bytes_written;
char expr_buffer[MAX_CHAR +1];
//elegxos ean grafthkan ta arxeia
struct stat file_stat;
off_t file_size;
int sync;
sleep(1);
fd5 = open(argv[1], O_RDWR | O_CREAT, NULL);
if (fd5 < 0){
perror("Error opening \"Channel_1.txt\".\n");
return(1);
}
fd2 = open(argv[2], O_RDWR | O_CREAT, NULL);
if (fd5 < 0){
perror("Error opening \"Channel_2.txt\".\n");
return(1);
}
while(1){
if (fstat(fd5, &file_stat) == -1) {
perror("Fstat.");
return(-1);
}
file_size = file_stat.st_size;
if (file_size == 0){
printf("\"Channel_1.txt\" is empty.\n");
}
else{
break;
}
}
offset = lseek(fd5, (off_t)(0*sizeof(char)), SEEK_SET);
if(lseek(fd5, 0*sizeof(char), SEEK_SET) < 0) {
printf("%d\n", errno);
perror("lseek to beginning of file: \"Channel_1.txt\"\n");
close(fd5);
return 1;
}
bytes_read = read(fd5, expr_buffer, MAX_CHAR*sizeof(char));
if (bytes_read < 0) {
perror("Read failure for file: \"Channel_1.txt\"\n");
close(fd5);
return 1;
}
当我执行程序，它说Channel_1.txt为空而没有edning。