动态连接4-readelf -S -s hello

[root@localhost mhello]# readelf -S hello
There are 30 section headers, starting at offset 0xadc:

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .interp           PROGBITS        08048134 000134 000013 00   A  0   0  1
  [ 2] .note.ABI-tag     NOTE            08048148 000148 000020 00   A  0   0  4
  [ 3] .note.gnu.build-i NOTE            08048168 000168 000024 00   A  0   0  4
  [ 4] .gnu.hash         GNU_HASH        0804818c 00018c 00003c 04   A  5   0  4
  [ 5] .dynsym           DYNSYM          080481c8 0001c8 0000e0 10   A  6   1  4
  [ 6] .dynstr           STRTAB          080482a8 0002a8 0000b1 00   A  0   0  1
  [ 7] .gnu.version      VERSYM          0804835a 00035a 00001c 02   A  5   0  2
  [ 8] .gnu.version_r    VERNEED         08048378 000378 000020 00   A  6   1  4
  [ 9] .rel.dyn          REL             08048398 000398 000008 08   A  5   0  4
  [10] .rel.plt          REL             080483a0 0003a0 000028 08   A  5  12  4
  [11] .init             PROGBITS        080483c8 0003c8 000030 00  AX  0   0  4
  [12] .plt              PROGBITS        080483f8 0003f8 000060 04  AX  0   0  4
  [13] .text             PROGBITS        08048460 000460 00021c 00  AX  0   0 16
  [14] .fini             PROGBITS        0804867c 00067c 00001c 00  AX  0   0  4
  [15] .rodata           PROGBITS        08048698 000698 000088 00   A  0   0  4
  [16] .eh_frame_hdr     PROGBITS        08048720 000720 00001c 00   A  0   0  4
  [17] .eh_frame         PROGBITS        0804873c 00073c 000058 00   A  0   0  4
  [18] .ctors            PROGBITS        08049794 000794 000008 00  WA  0   0  4
  [19] .dtors            PROGBITS        0804979c 00079c 000008 00  WA  0   0  4
  [20] .jcr              PROGBITS        080497a4 0007a4 000004 00  WA  0   0  4
  [21] .dynamic          DYNAMIC         080497a8 0007a8 0000d0 08  WA  6   0  4
  [22] .got              PROGBITS        08049878 000878 000004 04  WA  0   0  4
  [23] .got.plt          PROGBITS        0804987c 00087c 000020 04  WA  0   0  4
  [24] .data             PROGBITS        0804989c 00089c 000008 00  WA  0   0  4
  [25] .bss              NOBITS          080498a4 0008a4 000008 00  WA  0   0  4
  [26] .comment          PROGBITS        00000000 0008a4 00013b 00      0   0  1
  [27] .shstrtab         STRTAB          00000000 0009df 0000fc 00      0   0  1
  [28] .symtab           SYMTAB          00000000 000f8c 000480 10     29  46  4
  [29] .strtab           STRTAB          00000000 00140c 00025d 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings)
  I (info), L (link order), G (group), x (unknown)
  O (extra OS processing required) o (OS specific), p (processor specific)
[root@localhost mhello]# readelf -s hello

Symbol table '.dynsym' contains 14 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
     0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 00000000     4 OBJECT  GLOBAL DEFAULT  UND var_public_file_b
     2: 00000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
     3: 00000000     0 NOTYPE  WEAK   DEFAULT  UND _Jv_RegisterClasses
     4: 00000000   451 FUNC    GLOBAL DEFAULT  UND __libc_start_main@GLIBC_2.0 (2)
     5: 00000000    54 FUNC    GLOBAL DEFAULT  UND printf@GLIBC_2.0 (2)
     6: 00000000   460 FUNC    GLOBAL DEFAULT  UND puts@GLIBC_2.0 (2)
     7: 00000000   108 FUNC    GLOBAL DEFAULT  UND func_file_b
     8: 080498ac     0 NOTYPE  GLOBAL DEFAULT  ABS _end
     9: 080498a4     0 NOTYPE  GLOBAL DEFAULT  ABS _edata
    10: 0804869c     4 OBJECT  GLOBAL DEFAULT   15 _IO_stdin_used
    11: 080498a4     0 NOTYPE  GLOBAL DEFAULT  ABS __bss_start
    12: 080483c8     0 FUNC    GLOBAL DEFAULT   11 _init
    13: 0804867c     0 FUNC    GLOBAL DEFAULT   14 _fini

Symbol table '.symtab' contains 72 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
     0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 08048134     0 SECTION LOCAL  DEFAULT    1 
     2: 08048148     0 SECTION LOCAL  DEFAULT    2 
     3: 08048168     0 SECTION LOCAL  DEFAULT    3 
     4: 0804818c     0 SECTION LOCAL  DEFAULT    4 
     5: 080481c8     0 SECTION LOCAL  DEFAULT    5 
     6: 080482a8     0 SECTION LOCAL  DEFAULT    6 
     7: 0804835a     0 SECTION LOCAL  DEFAULT    7 
     8: 08048378     0 SECTION LOCAL  DEFAULT    8 
     9: 08048398     0 SECTION LOCAL  DEFAULT    9 
    10: 080483a0     0 SECTION LOCAL  DEFAULT   10 
    11: 080483c8     0 SECTION LOCAL  DEFAULT   11 
    12: 080483f8     0 SECTION LOCAL  DEFAULT   12 
    13: 08048460     0 SECTION LOCAL  DEFAULT   13 
    14: 0804867c     0 SECTION LOCAL  DEFAULT   14 
    15: 08048698     0 SECTION LOCAL  DEFAULT   15 
    16: 08048720     0 SECTION LOCAL  DEFAULT   16 
    17: 0804873c     0 SECTION LOCAL  DEFAULT   17 
    18: 08049794     0 SECTION LOCAL  DEFAULT   18 
    19: 0804979c     0 SECTION LOCAL  DEFAULT   19 
    20: 080497a4     0 SECTION LOCAL  DEFAULT   20 
    21: 080497a8     0 SECTION LOCAL  DEFAULT   21 
    22: 08049878     0 SECTION LOCAL  DEFAULT   22 
    23: 0804987c     0 SECTION LOCAL  DEFAULT   23 
    24: 0804989c     0 SECTION LOCAL  DEFAULT   24 
    25: 080498a4     0 SECTION LOCAL  DEFAULT   25 
    26: 00000000     0 SECTION LOCAL  DEFAULT   26 
    27: 00000000     0 FILE    LOCAL  DEFAULT  ABS crtstuff.c
    28: 08049794     0 OBJECT  LOCAL  DEFAULT   18 __CTOR_LIST__
    29: 0804979c     0 OBJECT  LOCAL  DEFAULT   19 __DTOR_LIST__
    30: 080497a4     0 OBJECT  LOCAL  DEFAULT   20 __JCR_LIST__
    31: 08048490     0 FUNC    LOCAL  DEFAULT   13 __do_global_dtors_aux
    32: 080498a4     1 OBJECT  LOCAL  DEFAULT   25 completed.5699
    33: 080498a8     4 OBJECT  LOCAL  DEFAULT   25 dtor_idx.5701
    34: 080484f0     0 FUNC    LOCAL  DEFAULT   13 frame_dummy
    35: 00000000     0 FILE    LOCAL  DEFAULT  ABS crtstuff.c
    36: 08049798     0 OBJECT  LOCAL  DEFAULT   18 __CTOR_END__
    37: 08048790     0 OBJECT  LOCAL  DEFAULT   17 __FRAME_END__
    38: 080497a4     0 OBJECT  LOCAL  DEFAULT   20 __JCR_END__
    39: 08048650     0 FUNC    LOCAL  DEFAULT   13 __do_global_ctors_aux
    40: 00000000     0 FILE    LOCAL  DEFAULT  ABS hello.c
    41: 00000000     0 FILE    LOCAL  DEFAULT  ABS file_a.c
    42: 0804987c     0 OBJECT  LOCAL  HIDDEN   23 _GLOBAL_OFFSET_TABLE_
    43: 08049794     0 NOTYPE  LOCAL  HIDDEN   18 __init_array_end
    44: 08049794     0 NOTYPE  LOCAL  HIDDEN   18 __init_array_start
    45: 080497a8     0 OBJECT  LOCAL  HIDDEN   21 _DYNAMIC
    46: 0804989c     0 NOTYPE  WEAK   DEFAULT   24 data_start
    47: 080485e0     5 FUNC    GLOBAL DEFAULT   13 __libc_csu_fini
    48: 08048460     0 FUNC    GLOBAL DEFAULT   13 _start
    49: 00000000     4 OBJECT  GLOBAL DEFAULT  UND var_public_file_b
    50: 00000000     0 NOTYPE  WEAK   DEFAULT  UND __gmon_start__
    51: 00000000     0 NOTYPE  WEAK   DEFAULT  UND _Jv_RegisterClasses
    52: 08048698     4 OBJECT  GLOBAL DEFAULT   15 _fp_hw
    53: 0804867c     0 FUNC    GLOBAL DEFAULT   14 _fini
    54: 0804857c    96 FUNC    GLOBAL DEFAULT   13 func_file_a
    55: 00000000   451 FUNC    GLOBAL DEFAULT  UND __libc_start_main@@GLIBC_
    56: 0804869c     4 OBJECT  GLOBAL DEFAULT   15 _IO_stdin_used
    57: 0804989c     0 NOTYPE  GLOBAL DEFAULT   24 __data_start
    58: 080498a0     4 OBJECT  GLOBAL DEFAULT   24 var_public_file_a
    59: 080486a0     0 OBJECT  GLOBAL HIDDEN   15 __dso_handle
    60: 080497a0     0 OBJECT  GLOBAL HIDDEN   19 __DTOR_END__
    61: 080485f0    90 FUNC    GLOBAL DEFAULT   13 __libc_csu_init
    62: 00000000    54 FUNC    GLOBAL DEFAULT  UND printf@@GLIBC_2.0
    63: 080498a4     0 NOTYPE  GLOBAL DEFAULT  ABS __bss_start
    64: 08048514    20 FUNC    GLOBAL DEFAULT   13 func_hello
    65: 080498ac     0 NOTYPE  GLOBAL DEFAULT  ABS _end
    66: 00000000   460 FUNC    GLOBAL DEFAULT  UND puts@@GLIBC_2.0
    67: 080498a4     0 NOTYPE  GLOBAL DEFAULT  ABS _edata
    68: 00000000   108 FUNC    GLOBAL DEFAULT  UND func_file_b
    69: 0804864a     0 FUNC    GLOBAL HIDDEN   13 __i686.get_pc_thunk.bx
    70: 08048528    84 FUNC    GLOBAL DEFAULT   13 main
    71: 080483c8     0 FUNC    GLOBAL DEFAULT   11 _init