プログラマ専用SNS ミクプラ

コード:

#include <stdio.h>   // fopen, fclose, fprintf, puts
#include <unistd.h>  // getpid, sleep

int main(void)
{
    pid_t pid = getpid();
    char *name = "/tmp/file1.txt";
    FILE *fp = fopen(name, "w");
    if (!fp) { puts("fopen failed"); return 1; }

    for (int i = 0; i < 10; i++) {
        fprintf(fp, "%d\n", i);
        fflush(fp);
        printf("%d: %d %s\n", i, pid, name);
        sleep(1);
    }
    fclose(fp);
}

コード:

#include <stdio.h>        // popen, pclose
#include <sys/inotify.h>  // inotify_init, inotify_add_watch
#include <unistd.h>       // read

int main(void)
{
    struct inotify_event *ie;
    char buf[4096], *p;
    int fd, wd, len;
    const char *name = "/tmp/file1.txt";

    fd = inotify_init();
    if (fd < 0) { puts("inotify_init failed"); return 1; }

    wd = inotify_add_watch(fd, name, IN_OPEN | IN_CLOSE | IN_MODIFY);
    if (wd < 0) { puts("inotifye_add_watch failed"); return 2; }

    while ((len = read(fd, buf, sizeof buf)) > 0) {
        for (p = buf; p < buf + len; p += sizeof(*ie) + ie->len) {
            ie = (struct inotify_event *) p;
            if (ie->mask & IN_MODIFY) {
                int pid;
                FILE *fp;
                char cmd[1024];
                sprintf(cmd, "lsof -Fp %s", name);
                fp = popen(cmd, "r");
                if (fp) {
                    if (fscanf(fp, "p%d", &pid) == 1)
                        printf("[%s] pid = %d\n", name, pid);
                    pclose(fp);
                }
            }
        }
    }
    close(fd);
    puts("done");
    return 0;
}