OS: Application Interaction

Firefox I/O

$ lsof -p $(pidof firefox)
[...]
firefox 32100 student   64u     IPv4           38654330       0t0      TCP so:44750->lb-140-82-112-26-iad.github.com:https (ESTABLISHED)
firefox 32100 student   65u     IPv4           38659353       0t0      TCP so:37528->239.237.117.34.bc.googleusercontent.com:https (ESTABLISHED)
[...]
firefox 32100 student  176u     unix 0x0000000000000000       0t0 38640969 type=SEQPACKET
firefox 32100 student  178u     unix 0x0000000000000000       0t0 38650545 type=SEQPACKET
firefox 32100 student  179u     unix 0x0000000000000000       0t0 38648379 type=STREAM
firefox 32100 student  181r     FIFO
 0,13       0t0 38640924 pipe
firefox 32100 student  185u  a_inode
 0,14         0    11438 [eventfd]
firefox 32100 student  186uw     REG
259,5    131072 17040026 /home/student/.mozilla/firefox/inonjd9q.default-release/protections.sqlite
firefox 32100 student  188u     unix 0x0000000000000000       0t0 38635209 type=STREAM
[...]
firefox 32100 student  200r      REG
  0,1      5196 14538955 /memfd:mozilla-ipc (deleted)
[...]

Exhibit 1

#include <stdio.h>

int main(void)
{
    printf("Hello, world\n");
    return 0;
}

Exhibit 2

// writer.c
int main(void)
{
    FILE *fp = fopen("myf.txt", "r");
    fprintf(fp, "Hello");
    fclose(fp);
    return 0;
}

// reader.c
int main(void)
{
    char a[20];
    FILE *fp = fopen("myf.txt", "r");
    fscanf(fp, "%s", a);
    printf("%s\n", a);
    fclose(fp);
    return 0;
}

Exhibit 3

int main(void)
{
    pid_t pid = fork();
    if (pid == 0) {
        sleep(2);
        exit(EXIT_SUCCESS);
    }

    waitpid(pid, &status, 0);

    return 0;
}