今天在下载mysql-server的时候，报错信息：
Can't exec "locale": No such file or directory at /usr/share/perl5/Debconf/Encoding.pm line 16.
Use of uninitialized value $Debconf::Encoding::charmap in scalar chomp at /usr/share/perl5/Debconf/Encoding.pm line 17.
Preconfiguring packages ...
dpkg: warning: 'ldconfig' not found in PATH or not executable
dpkg: error: 1 expected program not found in PATH or not executable
Note: root's PATH should usually contain /usr/local/sbin, /usr/sbin and /sbin
E: Sub-process /usr/bin/dpkg returned an error code (2)
这是因为找不到/sbin，目录下的ldconfig了。
解决：
sudo apt-get download libc-bin
dpkg -x libc-bin*.deb unpackdir/
sudo cp unpackdir/sbin/ldconfig /sbin/
sudo apt-get install --reinstall libc-bin
sudo apt-get -f install