Object dump using gobjdump on Mac OSX

gistfile1.txt

1. Write a hello hello world c

main( )
{
  printf("Hello World\n");
}


2. Compile it: gcc hello.c
Bonus: `gcc -Wall -save-temps hello.c -o hello` will give you extra stuff like: 
1. temp file (.i), 
2. intermediate file which has the machine code (.o) and 
3. assembly instructions (.s)

3. gobjdump -p a.out (Install binutils if you don't have it, port install binutils)

4. The object dump.

a.out:     file format mach-o-x86-64
Mach-O header:
 magic     : feedfacf
 cputype   : 01000007 (x86_64)
 cpusubtype: 80000003
 filetype  : 00000002 (execute)
 ncmds     : 0000000d (13)
 sizeofcmds: 00000620
 flags     : 00200085 (noundefs+dyldlink+twolevel+pie)
 reserved  : 00000000

Load command segment_64: name: __PAGEZERO
    vmaddr: 0000000000000000   vmsize: 0000000100000000
   fileoff: 0000000000000000 filesize: 0000000000000000 endoff: 0000000000000000
   nsects: 0   flags: 0

Load command segment_64: name: __TEXT
    vmaddr: 0000000100000000   vmsize: 0000000000001000
   fileoff: 0000000000000000 filesize: 0000000000001000 endoff: 0000000000001000
   nsects: 6   flags: 0
 Section: __text           __TEXT           (bfdname: .text)
  addr: 0000000100000ec0 size: 0000000000000060 offset: 0000000000000ec0
  align: 4  nreloc: 0  reloff: 0000000000000000
  flags: 80000400 (type: regular attr: some_instructions+pure_instructions)
  reserved1: 0x0  reserved2: 0x0  reserved3: 0x0
 Section: __stubs          __TEXT           (bfdname: __TEXT.__stubs)
  addr: 0000000100000f20 size: 000000000000000c offset: 0000000000000f20
  align: 1  nreloc: 0  reloff: 0000000000000000
  flags: 80000408 (type: symbol_stubs attr: some_instructions+pure_instructions)
  first indirect sym: 0 (2 entries)  stub size: 6  reserved3: 0x0
 Section: __stub_helper    __TEXT           (bfdname: __TEXT.__stub_helper)
  addr: 0000000100000f2c size: 0000000000000024 offset: 0000000000000f2c
  align: 2  nreloc: 0  reloff: 0000000000000000
  flags: 80000400 (type: regular attr: some_instructions+pure_instructions)
  reserved1: 0x0  reserved2: 0x0  reserved3: 0x0
 Section: __cstring        __TEXT           (bfdname: .cstring)
  addr: 0000000100000f50 size: 000000000000000c offset: 0000000000000f50
  align: 0  nreloc: 0  reloff: 0000000000000000
  flags: 00000002 (type: cstring_literals attr: -)
  reserved1: 0x0  reserved2: 0x0  reserved3: 0x0
 Section: __unwind_info    __TEXT           (bfdname: __TEXT.__unwind_info)
  addr: 0000000100000f5c size: 0000000000000050 offset: 0000000000000f5c
  align: 0  nreloc: 0  reloff: 0000000000000000
  flags: 00000000 (type: regular attr: -)
  reserved1: 0x0  reserved2: 0x0  reserved3: 0x0
 Section: __eh_frame       __TEXT           (bfdname: .eh_frame)
  addr: 0000000100000fb0 size: 0000000000000048 offset: 0000000000000fb0
  align: 3  nreloc: 0  reloff: 0000000000000000
  flags: 00000000 (type: regular attr: -)
  reserved1: 0x0  reserved2: 0x0  reserved3: 0x0

Load command segment_64: name: __DATA
    vmaddr: 0000000100001000   vmsize: 0000000000001000
   fileoff: 0000000000001000 filesize: 0000000000001000 endoff: 0000000000002000
   nsects: 4   flags: 0
 Section: __program_vars   __DATA           (bfdname: __DATA.__program_vars)
  addr: 0000000100001000 size: 0000000000000028 offset: 0000000000001000
  align: 4  nreloc: 0  reloff: 0000000000000000
  flags: 00000000 (type: regular attr: -)
  reserved1: 0x0  reserved2: 0x0  reserved3: 0x0
 Section: __nl_symbol_ptr  __DATA           (bfdname: .non_lazy_symbol_ptr)
  addr: 0000000100001028 size: 0000000000000010 offset: 0000000000001028
  align: 3  nreloc: 0  reloff: 0000000000000000
  flags: 00000006 (type: non_lazy_symbol_pointers attr: -)
  first indirect sym: 2 (2 entries)  reserved2: 0x0  reserved3: 0x0
 Section: __la_symbol_ptr  __DATA           (bfdname: .lazy_symbol_ptr)
  addr: 0000000100001038 size: 0000000000000010 offset: 0000000000001038
  align: 3  nreloc: 0  reloff: 0000000000000000
  flags: 00000007 (type: lazy_symbol_pointers attr: -)
  first indirect sym: 4 (2 entries)  reserved2: 0x0  reserved3: 0x0
 Section: __common         __DATA           (bfdname: __DATA.__common)
  addr: 0000000100001048 size: 0000000000000020 offset: 0000000000000000
  align: 3  nreloc: 0  reloff: 0000000000000000
  flags: 00000001 (type: zerofill attr: -)
  reserved1: 0x0  reserved2: 0x0  reserved3: 0x0

Load command segment_64: name: __LINKEDIT
    vmaddr: 0000000100002000   vmsize: 0000000000001000
   fileoff: 0000000000002000 filesize: 00000000000001f0 endoff: 00000000000021f0
   nsects: 0   flags: 0

Load command dyld_info:
       rebase: off: 0x00002000  size: 8       
         bind: off: 0x00002008  size: 24      
    weak bind: off: 0x00000000  size: 0       
    lazy bind: off: 0x00002020  size: 24      
       export: off: 0x00002038  size: 120     

Load command symtab:
   symoff: 0x000020b8    nsyms:       11  (endoff: 0x00002168)
   stroff: 0x00002180  strsize:      112  (endoff: 0x000021f0)

Load command dysymtab:
              local symbols: idx:          0  num: 1        (nxtidx: 1)
           external symbols: idx:          1  num: 7        (nxtidx: 8)
          undefined symbols: idx:          8  num: 3        (nxtidx: 11)
           table of content: off: 0x00000000  num: 0        (endoff: 0x00000000)
               module table: off: 0x00000000  num: 0        (endoff: 0x00000000)
   external reference table: off: 0x00000000  num: 0        (endoff: 0x00000000)
      indirect symbol table: off: 0x00002168  num: 6        (endoff: 0x00002180)
  external relocation table: off: 0x00000000  num: 0        (endoff: 0x00000000)
     local relocation table: off: 0x00000000  num: 0        (endoff: 0x00000000)
  indirect symbols:
  for section __TEXT.__stubs:
   0000000100000f20     0: 0x00000008 _exit
   0000000100000f26     1: 0x00000009 _puts
  for section __DATA.__nl_symbol_ptr:
   0000000100001028     2: 0x40000000 ABSOLUTE
   0000000100001030     3: 0x40000000 ABSOLUTE
  for section __DATA.__la_symbol_ptr:
   0000000100001038     4: 0x00000008 _exit
   0000000100001040     5: 0x00000009 _puts

Load command load_dylinker: /usr/lib/dyld

Load command uuid: 6e 36 a1 13 e1 4e 3e cc bc 81 b1 fa d9 6f d5 d3

Load command *UNKNOWN*:

Load command unixthread: nflavours: 1
   0: flavour: 0x00000004  offset: 0x00000550  size: 0x000000a8

Load command load_dylib: /usr/lib/libSystem.B.dylib
            time stamp: 0x00000002
       current version: 0x009f0100
  comptibility version: 0x00010000

Load command *UNKNOWN*:

Segments and Sections:
 #: Segment name     Section name     Address
[Segment __PAGEZERO       0000000000000000-00000000ffffffff ---]
[Segment __TEXT           0000000100000000-0000000100000fff r-x]
01: __TEXT           __text           0000000100000ec0 0000000000000060 80000400
02: __TEXT           __stubs          0000000100000f20 000000000000000c 80000408
03: __TEXT           __stub_helper    0000000100000f2c 0000000000000024 80000400
04: __TEXT           __cstring        0000000100000f50 000000000000000c 00000002
05: __TEXT           __unwind_info    0000000100000f5c 0000000000000050 00000000
06: __TEXT           __eh_frame       0000000100000fb0 0000000000000048 00000000
[Segment __DATA           0000000100001000-0000000100001fff rw-]
07: __DATA           __program_vars   0000000100001000 0000000000000028 00000000
08: __DATA           __nl_symbol_ptr  0000000100001028 0000000000000010 00000006
09: __DATA           __la_symbol_ptr  0000000100001038 0000000000000010 00000007
10: __DATA           __common         0000000100001048 0000000000000020 00000001
[Segment __LINKEDIT       0000000100002000-0000000100002fff r--]