环境：ubuntu 12.04lts 64bits + svn1.7.14
ubunut12.04默认装的svn是1.6版本，升级到1.7版本号后，执行svn命令出错：
symbol lookup error: /usr/local/lib/libsvn_subr-1.so.0: undefined symbol: apr_atomic_xchgptr
首先确保你安装了libapr和libapr-util：
chenww@chenww:/usr/lib$ sudo dpkg --list |grep apr
ii libapr1 1.4.6-1 Apache Portable Runtime Library
ii libaprutil1 1.3.12+dfsg-3 Apache Portable Runtime Utility Library
装过libapr和libaprutil会出现上述错误，是因为我们用的svn1.7是别人编译好的版本，编译的时候对lib库的依赖做了配置。查看依赖关系：
chenww@chenww:/usr/lib$ ldd /usr/lib/x86_64-linux-gnu/libsvn_subr-1.so.1
linux-vdso.so.1 => (0x00007fffd3dff000)
libaprutil-1.so.0 => /usr/local/lib/libaprutil-1.so.0 (0x00007fba44ec2000)
libapr-1.so.0 => /usr/local/lib/libapr-1.so.0 (0x00007fba44c99000)
libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007fba44a6e000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fba44857000)
libsqlite3.so.0 => /usr/lib/x86_64-linux-gnu/libsqlite3.so.0 (0x00007fba445b4000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fba44396000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fba43fd7000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fba43dcf000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007fba43b95000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fba43991000)
/lib64/ld-linux-x86-64.so.2 (0x00007fba45364000)
“罪魁祸首”找到了：
libaprutil-1.so.0 => /usr/local/lib/libaprutil-1.so.0 (0x00007fba44ec2000)
libapr-1.so.0 => /usr/local/lib/libapr-1.so.0 (0x00007fba44c99000)
lib库的位置进行了指定，12.04上，这两个库的位置在/usr/lib：
chenww@chenww:/usr/lib$ ll /usr/lib/libapr*
lrwxrwxrwx 1 root root 17 Mar 20 2012 /usr/lib/libapr-1.so.0 -> libapr-1.so.0.4.6
-rw-r--r-- 1 root root 234720 Mar 20 2012 /usr/lib/libapr-1.so.0.4.6
lrwxrwxrwx 1 root root 22 Feb 27 17:24 /usr/lib/libaprutil-1.so.0 -> libaprutil-1.so.0.3.12
-rw-r--r-- 1 root root 142840 Dec 19 2011 /usr/lib/libaprutil-1.so.0.3.12
lrwxrwxrwx 1 root root 32 Feb 27 17:22 /usr/lib/libaprutil-1.so.0.bak -> /usr/local/lib/libaprutil-1.so.0
在/usr/local/lib/下建立两个链接文件即可解决问题。
sudo ln -s /usr/lib/libapr-1.so.0 /usr/local/lib/libapr-1.so.0
sudo ln -s /usr/lib/libaprutil-1.so.0 /usr/local/lib/libaprutil-1.so.0