$ csound analog1.orc 
Localisation of messages is disabled, using default language.
time resolution is 1000.000 ns
Error opening plugin directory '/usr/lib/csound/plugins': No such file or directory
$ file `which csound`
/usr/bin/csound: ELF 64-bit LSB executable, x86-64, version 1 (SYSV),
dynamically linked (uses shared libs), for GNU/Linux 2.6.9, stripped
$ ll /usr/lib64/csound/plugins/
total 1292
-rwxr-xr-x 1 root root  10680 2007-04-04 17:56 libbabo.so*

etc...


Having the 32bit version installed at the same time means it ends up failing due
to the wrong ELF class..

WARNING: could not open library '/usr/lib/csound/plugins/libharmon.so'
(/usr/lib/csound/plugins/libharmon.so: wrong ELF class: ELFCLASS32)
WARNING: could not open library '/usr/lib/csound/plugins/libstdopcod.so'
(/usr/lib/csound/plugins/libstdopcod.so: wrong ELF class: ELFCLASS32)
WARNING: could not open library '/usr/lib/csound/plugins/libvaops.so'
(/usr/lib/csound/plugins/libvaops.so: wrong ELF class: ELFCLASS32)
WARNING: could not open library '/usr/lib/csound/plugins/librtalsa.so'
(/usr/lib/csound/plugins/librtalsa.so: wrong ELF class: ELFCLASS32)
WARNING: could not open library '/usr/lib/csound/plugins/libugakbari.so'
(/usr/lib/csound/plugins/libugakbari.so: wrong ELF class: ELFCLASS32)
WARNING: could not open library '/usr/lib/csound/plugins/libstdutil.so'
(/usr/lib/csound/plugins/libstdutil.so: wrong ELF class: ELFCLASS32)
WARNING: could not open library '/usr/lib/csound/plugins/libftest.so'
(/usr/lib/csound/plugins/libftest.so: wrong ELF class: ELFCLASS32)