Input / Output Error : Bad Blocks : How To Restart Linux

    # reboot
    bash: /sbin/reboot: Input/output error

    # shutdown -r now
    bash: /sbin/shutdown: Input/output error
    
Input/output error while running the command mostly due to two reason. 
Either it could be bad blocks on the disk or someone hacked your machine. 
In this situation first suggestion would be to check /var/log/messages for any disk 
related alerts (might see some sense key alerts).

    tail -n 100 /var/log/messages
    tail -f /var/log/messages    
    
    
Forced Reboot
    echo 1 > /proc/sys/kernel/sysrq
    echo b > /proc/sysrq-trigger

Forced Shutdown
    echo 1 > /proc/sys/kernel/sysrq
    echo o > /proc/sysrq-trigger