安装好Apache，启动时提示找不到libpcre.so.1：
/usr/local/apache2/bin/httpd: error while loading shared libraries: libpcre.so.1: cannot open shared object file: No such file or directory
使用ldd查看httpd的依赖库信息：
# ldd httpd linux-vdso.so.1 => (0x00007fff691ff000) libpcre.so.1 => not found libaprutil-1.so.0 => /usr/local/apache2/lib/libaprutil-1.so.0 (0x00007ff847f31000) libapr-1.so.0 => /usr/local/apache2/lib/libapr-1.so.0 (0x00007ff847d00000) libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007ff847ae3000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ff847726000) libexpat.so.0 => /usr/local/apache2/lib/libexpat.so.0 (0x00007ff8474fb000) libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007ff8472c2000) libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ff8470be000) /lib64/ld-linux-x86-64.so.2 (0x00007ff848165000)
libpcre.so.1库果然没有找到。
解决方法：
1. 搜索libpcre.so.1文件，发现该文件在/usr/local/lib目录下。
2. 在/etc/ld.so.conf.d目录下新建文件libc.conf，将/usr/local/lib目录加到该文件：
/usr/local/lib
3. 执行ldconfig命令：
sudo ldconfig
4. 使用ldd命令确认libpcre.so.1是否已找到：
# ldd httpd linux-vdso.so.1 => (0x00007fffcc3ff000) libpcre.so.1 => /usr/local/lib/libpcre.so.1 (0x00007f2f68f98000) libaprutil-1.so.0 => /usr/local/apache2/lib/libaprutil-1.so.0 (0x00007f2f68d76000) libapr-1.so.0 => /usr/local/apache2/lib/libapr-1.so.0 (0x00007f2f68b45000) libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f2f68928000) libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f2f6856b000) libexpat.so.0 => /usr/local/apache2/lib/libexpat.so.0 (0x00007f2f68340000) libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007f2f68107000) libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f2f67f03000) /lib64/ld-linux-x86-64.so.2 (0x00007f2f691c7000)