testpipe1.c

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <stdlib.h>

int main()
{
    pid_t pid;
    int cnt = 0;
    int pipefd[2];
    char buf;
    char received[20];
    int receivep = 0;
    char w[12];
    char r[12];
    
    if (pipe(pipefd) == -1)
    {
        printf("pipe");
        exit(-1);
    }
    write(pipefd[1], "test", strlen("test"));
    close(pipefd[1]);
    while (read(pipefd[0], &buf, 1) > 0)
        received[receivep++] = buf;
    received[receivep] = 0;
    receivep = 0;
    assert(strcmp(received, "test") == 0);
    close(pipefd[0]);

    if (pipe(pipefd) == -1)
    {
        printf("pipe");
        exit(-1);
    }
    sprintf(w, "%d", pipefd[1]);
    sprintf(r, "%d", pipefd[0]);
    pid = vfork();
    if (pid < 0)
        printf("error in fork!\n");
    else if (pid == 0)
    {
        execl("/bin/testpipe2", "/bin/testpipe2", r, w, NULL);
        exit(0);
    }
    else if (pid > 0)
    {
        close(pipefd[1]);
        while (read(pipefd[0], &buf, 1) > 0)
            received[receivep++] = buf;
        received[receivep] = 0;
        assert(strcmp(received, "hello pipe") == 0);
        close(pipefd[0]);
    }
    return 0;
}