[arch-dev-public] bash 4.0 / readline 6.0 rebuilds

Thomas Bächler thomas at archlinux.org
Sun Mar 1 04:56:06 EST 2009

Allan McRae schrieb:
>> Don't use ldd here, as it also covers indirect dependencies. If libA 
>> depends on libB and libB depends on libC, then only libB needs 
>> updating when libC changes the SOname, as long as libA never calls 
>> libC directly.
>> You should parse the output of readelf -d, which only shows direct 
>> dependencies and thus allows you to distinguish between direct and 
>> indirect dependencies ... at least as far as I understand it.
> That does not matter when done in a very minimal chroot as directed at 
> the top of the script.  If libA depends on libB and libB depends on 
> libC, and libB is not on the system, then "ldd libC" does not show libA.

You're looking at this the wrong way: You want to know whether libA 
needs a rebuild because of the libC SONAME bump. So, you install libA 
and all its dependencies (libB and libC). Now ldd libA.so shows that it 
depends on libC (but the truth is that only libB requires libC, but libA 
does not), while readelf tells you libA does NOT need libC.

Even better, you don't need to install all dependencies! You just need 
to extract libA and use readelf on it!

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