readelf komutu

-d seçeneği
dynamic section hakkında bilgi gösterir. Şöyle yaparız.

readelf -d a.out

NEEDED alanı
Eğer bir .so kütüphanesi bir başka .so kütüphanesine bağımlıysa elf dosyasında bu alan NEEDED olarak işaretlidir.  Şöyle yaparız.

$ readelf -d liba.so | grep NEEDED
 0x00000001 (NEEDED)                     Shared library: [libc.so.6]

-debug-dump seçeneği

debug section hakkında bilgi gösterir. Açıklaması şöyle.

The .debug_info section contains the actual debugging information. This section does not contain strings.

Şöyle yaparız.

readelf --debug-dump filename.o

Çıktı olarak şunu alırız.

    ...
Item 123:
    Type of information: Data type
    Name: 2b /* String #2b in ".debug_str" is "int" */
    Kind of data type: Signed integer
    Number of bits: 32
    ... some more information ...
Item 124:
    Type of information: Global variable
    Name: 8 /* "lvar" */
    Data type defined by: Item 123
    Stored at: Address 0x1234
    ... some more information ...
Begin item 125:
    Type of information: Function
    Name: 6 /* "main" */
    ... some more information ...
Item 126:
    Type of information: Local variable
    Name: 5 /* "svar" */
    Data type defined by: Item 123
    Stored at: Address 0x1238
    ... some more information ...
End item 125 /* Function "main" */
Item 127:
    ...

- h seçeneği
Header bilgisini gösterir. Şöyle yaparız.

readelf -h MyApp

Çıktı olarak şunu alırız.

ELF Header:
  Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              REL (Relocatable file)
  Machine:                           Intel 80386
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          2548 (bytes into file)
  Flags:                             0x0
  Size of this header:               52 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           40 (bytes)
  Number of section headers:         16
  Section header string table index: 13

Class alanı 32/64 bit olduğunu gösterir. 64 bit uygulamanın çıktısı şöyledir.

ELF Header:
Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 
Class:                             ELF64
Data:                              2's complement, little endian
Version:                           1 (current)
OS/ABI:                            UNIX - System V
ABI Version:                       0
Type:                              DYN (Shared object file)
Machine:                           Advanced Micro Devices X86-64
Version:                           0x1
Entry point address:               0x1158
Start of program headers:          64 (bytes into file)
Start of section headers:          308248 (bytes into file)
Flags:                             0x0

-S seçeneği
Section'lar hakkında bilgi gösterir. Şöyle yaparız.

$ readelf -S true
There are 30 section headers, starting at offset 0x7368:

Section Headers:
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
  [ 0]                   NULL             0000000000000000  00000000
       0000000000000000  0000000000000000           0     0     0
  [ 1] .interp           PROGBITS         0000000000000238  00000238
       000000000000001c  0000000000000000   A       0     0     1
  [ 2] .note.ABI-tag     NOTE             0000000000000254  00000254
       0000000000000020  0000000000000000   A       0     0     4
  [ 3] .note.gnu.build-i NOTE             0000000000000274  00000274
       0000000000000024  0000000000000000   A       0     0     4
  ...
  [23] .dynamic          DYNAMIC          0000000000206dd8  00006dd8
       00000000000001e0  0000000000000010  WA       6     0     8
  [24] .got              PROGBITS         0000000000206fb8  00006fb8
       0000000000000030  0000000000000008  WA       0     0     8
  [25] .got.plt          PROGBITS         0000000000207000  00007000
       0000000000000188  0000000000000008  WA       0     0     8
  [26] .data             PROGBITS         00000000002071a0  000071a0
       0000000000000080  0000000000000000  WA       0     0     32
  [27] .bss              NOBITS           0000000000207220  00007220
       00000000000001a0  0000000000000000  WA       0     0     32
  [28] .gnu_debuglink    PROGBITS         0000000000000000  00007220
       0000000000000034  0000000000000000           0     0     1
  [29] .shstrtab         STRTAB           0000000000000000  00007254
       000000000000010f  0000000000000000           0     0     1