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Old 10-19-2010, 02:44 AM   #1
divyavyas
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how does ldd command knows about depending shared objects


hi,

I would like to know how ldd command detects the depending shared object .
I have gone through /bin/ldd script but did not got anything.

I am new to linux .Please give me some idea.
 
Old 10-19-2010, 05:47 AM   #2
kbp
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It probably reads the import table of the binary .. you may want to look at doco on the ELF file format

cheers
 
Old 10-20-2010, 10:00 AM   #3
Valery Reznic
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Quote:
Originally Posted by kbp View Post
It probably reads the import table of the binary .. you may want to look at doco on the ELF file format

cheers
No, ldd (on Linux) run executable in question with environment variable LD_TRACE_LOADED_OBJECTS set, and it tell to ld-linux not actually run the program, but only dump it's dependencies.

ldd is actually a script, so you can have a look yourself
 
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Old 10-20-2010, 10:37 AM   #4
wikapuki
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Hi,

I am sure you meant as your posting read, but just incase you meant show me an example of how it works:

I use it to find out what library's are no longer installed after an update on my AMD64 which are needed for skype bit binary. SO I do the following:
ldd /usr/bin/skype | grep 'not found'

or without the filter:

ldd /usr/bin/skype
linux-gate.so.1 => (0xf77d7000)
libasound.so.2 => /usr/lib32/libasound.so.2 (0xf76ea000)
libXv.so.1 => /usr/lib32/libXv.so.1 (0xf76e5000)
libXss.so.1 => /usr/lib32/libXss.so.1 (0xf76e1000)
libSM.so.6 => /usr/lib32/libSM.so.6 (0xf76d9000)
libICE.so.6 => /usr/lib32/libICE.so.6 (0xf76c1000)
libXi.so.6 => /usr/lib32/libXi.so.6 (0xf76b4000)
libXrender.so.1 => /usr/lib32/libXrender.so.1 (0xf76ab000)
libXrandr.so.2 => /usr/lib32/libXrandr.so.2 (0xf76a4000)
libfreetype.so.6 => /usr/lib32/libfreetype.so.6 (0xf762c000)
libfontconfig.so.1 => /usr/lib32/libfontconfig.so.1 (0xf75fd000)
libXext.so.6 => /usr/lib32/libXext.so.6 (0xf75ee000)
libX11.so.6 => /usr/lib32/libX11.so.6 (0xf74d1000)
libz.so.1 => /usr/lib32/libz.so.1 (0xf74bc000)
libgthread-2.0.so.0 => /usr/lib32/libgthread-2.0.so.0 (0xf74b6000)
libglib-2.0.so.0 => /lib32/libglib-2.0.so.0 (0xf73ed000)
librt.so.1 => /lib32/librt.so.1 (0xf73e4000)
libdl.so.2 => /lib32/libdl.so.2 (0xf73e0000)
libpthread.so.0 => /lib32/libpthread.so.0 (0xf73c7000)
libstdc++.so.6 => /usr/lib32/libstdc++.so.6 (0xf72d2000)
libm.so.6 => /lib32/libm.so.6 (0xf72ab000)
libgcc_s.so.1 => /usr/lib32/libgcc_s.so.1 (0xf728d000)
libc.so.6 => /lib32/libc.so.6 (0xf7146000)
libuuid.so.1 => /lib32/libuuid.so.1 (0xf7142000)
libexpat.so.1 => /usr/lib32/libexpat.so.1 (0xf711c000)
libxcb.so.1 => /usr/lib32/libxcb.so.1 (0xf7102000)
libpcre.so.3 => /lib32/libpcre.so.3 (0xf70cf000)
/lib/ld-linux.so.2 (0xf77d8000)
libXau.so.6 => /usr/lib32/libXau.so.6 (0xf70cc000)
libXdmcp.so.6 => /usr/lib32/libXdmcp.so.6 (0xf70c7000)
 
Old 10-21-2010, 12:11 AM   #5
divyavyas
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thanks............but my doubt is still there .........not able to visualize
 
  


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