The following code is example code of the book "Beginning Linux Programming 3rd Edition" ....
I've compiled and ran it...it's work...
Can anyone tell me why the child process can read data from file_pipes[0] while thd file_pipes[0] was closed...
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#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
int main()
{
int data_processed;
int file_pipes[2];
const char some_data[] = "123";
pid_t fork_result;
if (pipe(file_pipes) == 0) {
fork_result = fork();
if (fork_result == (pid_t)-1) {
fprintf(stderr, "Fork failure");
exit(EXIT_FAILURE);
}
if (fork_result == (pid_t)0) {
close(0);
dup(file_pipes[0]);
close(file_pipes[0]); //Here!!!!...I don't know why?
close(file_pipes[1]);
execlp("od", "od", "-c", (char *)0);
exit(EXIT_FAILURE);
}
else {
close(file_pipes[0]);
data_processed = write(file_pipes[1], some_data,
strlen(some_data));
close(file_pipes[1]);
printf("%d - wrote %d bytes\n", (int)getpid(), data_processed);
}
}
exit(EXIT_SUCCESS);
}