@wallhackio UNIXv7, /usr/src/cmd/size.c:

#include    <stdio.h>
#include    <a.out.h>

/*
    size -- determine object size

*/

int a_magic[] = {A_MAGIC1,A_MAGIC2,A_MAGIC3,A_MAGIC4,0};

main(argc, argv)
char **argv;
{
    struct exec buf;
    long sum;
    int gorp,i;
    FILE *f;

    if (argc==1) {
        *argv = "a.out";
        argc++;
        --argv;
    }
    gorp = argc;
    while(--argc) {
        ++argv;
        if ((f = fopen(*argv, "r"))==NULL) {
            printf("size: %s not found\n", *argv);
            continue;
        }
        fread((char *)&buf, sizeof(buf), 1, f);
        for(i=0;a_magic[i];i++)
            if(a_magic[i] == buf.a_magic) break;
        if(a_magic[i] == 0) {
            printf("size: %s not an object file\n", *argv);
            fclose(f);
            continue;
        }
        if (gorp>2)
            printf("%s: ", *argv);
        printf("%u+%u+%u = ", buf.a_text,buf.a_data,buf.a_bss);
        sum = (long) buf.a_text + (long) buf.a_data + (long) buf.a_bss;
        printf("%Db = 0%Ob\n", sum, sum);
        fclose(f);
    }
}