readelf vs. objdump: tại sao cả hai cần

Question

Tôi cần tìm hiểu về bố cục tệp ELF cho dự án tôi đang làm việc và tôi nhận thấy sự tồn tại của các công cụ này. Tại sao tất cả các bản phân phối Linux bao gồm cả đọc và objdump? Những công cụ này có bổ sung cho nhau không? Khi nào tôi thích sử dụng cái khác?

Answer 1

từ binutils/readelf.c:

/* The difference between readelf and objdump: 

    Both programs are capabale of displaying the contents of ELF format files, 
    so why does the binutils project have two file dumpers ? 

    The reason is that objdump sees an ELF file through a BFD filter of the 
    world; if BFD has a bug where, say, it disagrees about a machine constant 
    in e_flags, then the odds are good that it will remain internally 
    consistent. The linker sees it the BFD way, objdump sees it the BFD way, 
    GAS sees it the BFD way. There was need for a tool to go find out what 
    the file actually says. 

    This is why the readelf program does not link against the BFD library - it 
    exists as an independent program to help verify the correct working of BFD. 

    There is also the case that readelf can provide more information about an 
    ELF file than is provided by objdump. In particular it can display DWARF 
    debugging information which (at the moment) objdump cannot. */