前段时间想学习以下Latex编辑器，于是装了个集成开发环境Kile，但是一直运行不起来，在终端下运行时显示的错误是‘symbol lookup error: /usr/lib/libQtSvg.so.4: undefined symbol ......'，到网上查了很长时间都没有找到解决办法。今天有时间又弄了以下，觉得是动态库的问题，ldd /usr/bin/kile，果然，看到结果后就可以确定问题是出在LD_LIBRARY_PATH这个环境变量上了，

    linux-gate.so.1 =>  (0x00671000)
    libkhtml.so.5 => /usr/lib/libkhtml.so.5 (0x06640000)
    libkrosscore.so.4 => /usr/lib/libkrosscore.so.4 (0x00294000)
    libkfile.so.4 => /usr/lib/libkfile.so.4 (0x06d18000)
    libktexteditor.so.4 => /usr/lib/libktexteditor.so.4 (0x042ed000)
    libkparts.so.4 => /usr/lib/libkparts.so.4 (0x04bc7000)
    libkjs.so.4 => /usr/lib/libkjs.so.4 (0x04d65000)
    libQtScript.so.4 => /usr/lib/libQtScript.so.4 (0x06392000)
    libkio.so.5 => /usr/lib/libkio.so.5 (0x060f8000)
    libQtXml.so.4 => /opt/programs/altera/10.0/quartus/linux/libQtXml.so.4 (0x001f2000)
    libnepomuk.so.4 => /usr/lib/libnepomuk.so.4 (0x007cf000)
    libsoprano.so.4 => /usr/lib/libsoprano.so.4 (0x04135000)
    libQtNetwork.so.4 => /opt/programs/altera/10.0/quartus/linux/libQtNetwork.so.4 (0x002b2000)
    libkdeui.so.5 => /usr/lib/libkdeui.so.5 (0x05ceb000)
    libQtSvg.so.4 => /usr/lib/libQtSvg.so.4 (0x006f6000)
    libkdecore.so.5 => /usr/lib/libkdecore.so.5 (0x04f80000)
    libQtCore.so.4 => /opt/programs/altera/10.0/quartus/linux/libQtCore.so.4 (0x003d8000)
    libpthread.so.0 => /lib/libpthread.so.0 (0x00c88000)
    libQtDBus.so.4 => /usr/lib/libQtDBus.so.4 (0x00110000)
    libQtGui.so.4 => /opt/programs/altera/10.0/quartus/linux/libQtGui.so.4 (0x00ca3000)
    libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x008ae000)
    libm.so.6 => /lib/libm.so.6 (0x00c5c000)
    libgcc_s.so.1 => /opt/programs/altera/10.0/quartus/linux/libgcc_s.so.1 (0x00189000)
    libc.so.6 => /lib/libc.so.6 (0x00ad0000)
    libphonon.so.4 => /usr/lib/libphonon.so.4 (0x04ea0000)
    libjpeg.so.62 => /usr/lib/libjpeg.so.62 (0x04c8b000)
    libgif.so.4 => /usr/lib/libgif.so.4 (0x0074d000)
    libpng12.so.0 => /usr/lib/libpng12.so.0 (0x00194000)
    libz.so.1 => /lib/libz.so.1 (0x001bc000)
    libSM.so.6 => /usr/lib/libSM.so.6 (0x00a9c000)
    libICE.so.6 => /usr/lib/libICE.so.6 (0x047be000)
    libX11.so.6 => /usr/lib/libX11.so.6 (0x0536e000)
    libXext.so.6 => /usr/lib/libXext.so.6 (0x001d1000)
    libXft.so.2 => /usr/lib/libXft.so.2 (0x00a64000)
    libXau.so.6 => /usr/lib/libXau.so.6 (0x001e2000)
    libXpm.so.4 => /usr/lib/libXpm.so.4 (0x0088b000)
    libsolid.so.4 => /usr/lib/libsolid.so.4 (0x0421e000)
    libXrender.so.1 => /usr/lib/libXrender.so.1 (0x001e5000)
    libpcre.so.0 => /lib/libpcre.so.0 (0x04c44000)
    libpcreposix.so.0 => /usr/lib/libpcreposix.so.0 (0x001ee000)
    libstreamanalyzer.so.0 => /usr/lib/libstreamanalyzer.so.0 (0x0099f000)
    libstreams.so.0 => /usr/lib/libstreams.so.0 (0x042b2000)
    libacl.so.1 => /lib/libacl.so.1 (0x04b4b000)
    libattr.so.1 => /lib/libattr.so.1 (0x04aff000)
    libsopranoclient.so.1 => /usr/lib/libsopranoclient.so.1 (0x006a2000)
    libdbusmenu-qt.so.2 => /usr/lib/libdbusmenu-qt.so.2 (0x00265000)
    libXtst.so.6 => /usr/lib/libXtst.so.6 (0x00a59000)
    libXcursor.so.1 => /usr/lib/libXcursor.so.1 (0x00238000)
    libXfixes.so.3 => /usr/lib/libXfixes.so.3 (0x00242000)
    libbz2.so.1 => /lib/libbz2.so.1 (0x04a90000)
    liblzma.so.0 => /usr/lib/liblzma.so.0 (0x04b23000)
    libresolv.so.2 => /lib/libresolv.so.2 (0x00247000)
    libfam.so.0 => /usr/lib/libfam.so.0 (0x00668000)
    libdl.so.2 => /lib/libdl.so.2 (0x00672000)
    librt.so.1 => /lib/librt.so.1 (0x00677000)
    /lib/ld-linux.so.2 (0x00aaf000)
    libdbus-1.so.3 => /lib/libdbus-1.so.3 (0x00782000)
    libfreetype.so.6 => /usr/lib/libfreetype.so.6 (0x01716000)
    libfontconfig.so.1 => /usr/lib/libfontconfig.so.1 (0x00a1c000)
    libglib-2.0.so.0 => /lib/libglib-2.0.so.0 (0x017a8000)
    libpulse.so.0 => /usr/lib/libpulse.so.0 (0x0448f000)
    libpulse-mainloop-glib.so.0 => /usr/lib/libpulse-mainloop-glib.so.0 (0x00a8e000)
    libuuid.so.1 => /lib/libuuid.so.1 (0x00680000)
    libxcb.so.1 => /usr/lib/libxcb.so.1 (0x00756000)
    libxml2.so.2 => /usr/lib/libxml2.so.2 (0x04340000)
    libXi.so.6 => /usr/lib/libXi.so.6 (0x00685000)
    libexpat.so.1 => /lib/libexpat.so.1 (0x018b6000)
    libpulsecommon-0.9.21.so => /usr/lib/libpulsecommon-0.9.21.so (0x045b1000)
    libwrap.so.0 => /lib/libwrap.so.0 (0x00a83000)
    libsndfile.so.1 => /usr/lib/libsndfile.so.1 (0x04b55000)
    libasyncns.so.0 => /usr/lib/libasyncns.so.0 (0x00a7b000)
    libnsl.so.1 => /lib/libnsl.so.1 (0x04b06000)
    libFLAC.so.8 => /usr/lib/libFLAC.so.8 (0x04d26000)
    libvorbisenc.so.2 => /usr/lib/libvorbisenc.so.2 (0x0487b000)
    libvorbis.so.0 => /usr/lib/libvorbis.so.0 (0x04aab000)
    libogg.so.0 => /usr/lib/libogg.so.0 (0x04aa3000)

红色部分就是问题之所在，由于之前在安装quartus的时候设置了一个so的路径，还以为LD_LIBRARY_PATH和PATH一样的都是按顺序查找各个部分呢，但是LD_LIBRARY_PATH是加在系统默认的加载路径之前的，'This list is prepended to the existing list of compiled-in loader paths for a given executable, and any system default loader paths'，那么这个问题就和上次的那个nautilus程序的问题一样，都是连接到了错误的so文件，导致符号找不到或版本问题。

'LD_LIBRARY_PATH is handy for development and testing, but shouldn't be modified by an installation process for normal use by normal users; see ``Why LD_LIBRARY_PATH is Bad'' at http://www.visi.com/~barr/ldpath.html for an explanation of why'，原文是这么说的，这个环境变量主要用于开发和测试阶段，不适合在应用程序的安装过程中修改。。