Used for example:
- by Monero to hide the input of a transaction
- anonymous electronic voting
Running:outputs:
readelf -h hello_world.o
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: REL (Relocatable file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x0
Start of program headers: 0 (bytes into file)
Start of section headers: 64 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 0 (bytes)
Number of program headers: 0
Size of section headers: 64 (bytes)
Number of section headers: 7
Section header string table index: 3
Running:outputs:
readelf -h hello_world.out
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: EXEC (Executable file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x4000b0
Start of program headers: 64 (bytes into file)
Start of section headers: 272 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 2
Size of section headers: 64 (bytes)
Number of section headers: 6
Section header string table index: 3
Bytes in the object file:
00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
00000010 01 00 3e 00 01 00 00 00 00 00 00 00 00 00 00 00 |..>.............|
00000020 00 00 00 00 00 00 00 00 40 00 00 00 00 00 00 00 |........@.......|
00000030 00 00 00 00 40 00 00 00 00 00 40 00 07 00 03 00 |....@.....@.....|
Executable:
00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
00000010 02 00 3e 00 01 00 00 00 b0 00 40 00 00 00 00 00 |..>.......@.....|
00000020 40 00 00 00 00 00 00 00 10 01 00 00 00 00 00 00 |@...............|
00000030 00 00 00 00 40 00 38 00 02 00 40 00 06 00 03 00 |....@.8...@.....|
Structure represented:
# define EI_NIDENT 16
typedef struct {
unsigned char e_ident[EI_NIDENT];
Elf64_Half e_type;
Elf64_Half e_machine;
Elf64_Word e_version;
Elf64_Addr e_entry;
Elf64_Off e_phoff;
Elf64_Off e_shoff;
Elf64_Word e_flags;
Elf64_Half e_ehsize;
Elf64_Half e_phentsize;
Elf64_Half e_phnum;
Elf64_Half e_shentsize;
Elf64_Half e_shnum;
Elf64_Half e_shstrndx;
} Elf64_Ehdr;
Manual breakdown:
- 0 0:
EI_MAG
=7f 45 4c 46
=0x7f 'E', 'L', 'F'
: ELF magic number - 0 4:
EI_CLASS
=02
=ELFCLASS64
: 64 bit elf - 0 5:
EI_DATA
=01
=ELFDATA2LSB
: little endian data - 0 6:
EI_VERSION
=01
: format version - 0 7:
EI_OSABI
(only in 2003 Update) =00
=ELFOSABI_NONE
: no extensions. - 0 8:
EI_PAD
= 8x00
: reserved bytes. Must be set to 0. - On the executable it is
02 00
forET_EXEC
.Another important possibility for the executable isET_DYN
for PIE executables and shared libraries.ET_DYN
tells the Linux kernel that the code is position independent, and can loaded at a random memory location with ASLR. - 1 2:
e_machine
=3e 00
=62
=EM_X86_64
: AMD64 architecture - 1 4:
e_version
=01 00 00 00
: must be 1 - 1 8:
e_entry
= 8x00
: execution address entry point, or 0 if not applicable like for the object file since there is no entry point.On the executable, it isb0 00 40 00 00 00 00 00
. The kernel puts the RIP directly on that value when executing. It can be configured by the linker script or-e
. But it will segfault if you set it too low: stackoverflow.com/questions/2187484/why-is-the-elf-execution-entry-point-virtual-address-of-the-form-0x80xxxxx-and-n 40 00 00 00
on the executable, i.e. it starts immediately after the ELF header.- 2 8:
e_shoff
=40
7x00
=0x40
: section header table file offset, 0 if not present. The Intel386 architecture defines no flags; so this member contains zero.
- 3 4:
e_ehsize
=40 00
: size of this elf header. TODO why this field needed? Isn't the size fixed? 38 00
on executable: it is 56 bytes long02 00
on executable: there are 2 entries.- 3 A:
e_shentsize
ande_shnum
=40 00 07 00
: section header size and number of entries - 3 E:
e_shstrndx
(Section Header STRing iNDeX
) =03 00
: index of the.shstrtab
section.
The Great Sage, Heaven's Equal (Strange Tales from a Chinese Studio story) Updated 2025-07-11 +Created 1970-01-01
The frequency range of Wi-Fi, which falls in the microwave range, is likely chosen to allow faster data transfer than say, FM broadcasting, while still being relatively transparent to walls (though not as much).
No mention of education specifically on website. But at www.washingtonpost.com/wp-srv/liveonline/00/business/saylor0621.htm from Michael J. Saylor they did show interest, so adding to this Educational charitable organization list anyways.
There are unlisted articles, also show them or only show them.