Mach-O load commands

load-command = cmdtype cmdsize (segment-command | dylib-command | symtab-command | dysymtab-command | dyld-info-command | ...)

  struct load_command {
    uint32_t cmd;       /* type of load command */
    uint32_t cmdsize;   /* total size of command in bytes */
  };

Some commands are for loaders, and the others are for linkers

Can be shown by otool -l

  % otool -l /usr/bin/gcc