CentOS restore library
/lib64/libc.so.6 many as a library file command, this will cause a command not working. This article is to address this issue 
after the emergence of the phenomenon shown above, turn off the power back on, press the Esc key to enter the fast rescue (rescue mode)
1. The boundary screen with a selection to boot from CD files; because my system by iso image files installed. At this time to ensure that the CD image files in the mounted state is 
2. Select the Troubleshooting 
3. Select rescue mode 
4. Enter a carriage return, the original system disk is mounted to the rescue mode system mnt / lower / sysimage, selection the original system disk
permissions: continue (maintain the status quo)
the following prompt means using the command chroot / mnt / sysimage can rescue system after entering the / mnt / sysimage as the original
system /. Enter here to do a direct deal you can skip 
5. Enter the linux rescue mode system
restore system libraries
1) Find libc.so.6 file location in the rescue mode;
2) View original system disk partitions are linked to load the next / mnt / sysimage, the original system / is now / mnt / sysimage 
6.cp rescue mode libc.so.6 library files to the original system disks / lib64 
after 7.exit quit automatically reboot into The system everything back to normal