Dump SYSV shared memory segment to stdout

shmdump.c

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/shm.h>

int main(int argc, char**argv)
{
    void *shm;

    if (argc != 4) {
        fprintf(stderr, "usage: %s shmid offset length\n", argv[0]);
        return 1;
    }
    shm = shmat(atoi(argv[1]), NULL, SHM_RDONLY);
    if (shm == (void*)-1) {
        fprintf(stderr, "shmat() failed: %s\n", strerror(errno));
        return errno;
    }
    write(1, shm+atoi(argv[2]), atoi(argv[3]));
    return 0;
}