This text address: http://www.cnblogs.com/lzhskywalker/archive/2012/07/20/2600854.html
The new company's office computer for the Ubuntu 12.04 LTS version, accustomed to the Linux will be left CTRL and CapsLock Exchange, find to Xmodmap, found that the system has been installed by default, according to the example given in man Xmodmap, the keys are exchanged, the code is as follows
Remove lock = caps_lockremove Control = Control_lkeysym control_l = Caps_lockkeysym Caps_lock = Control_ladd lock = Caps_L Ockadd Control = control_l
Put the above code into ~/. Xmodmap, logout log in again.
After testing, on Ubuntu 12.04, if placed in the ~ directory, the file name must be written as above, case-sensitive, simply log off and re-login to take effect without restarting.
If the temporary changes, you can directly put the code in any file to execute xmodmap+ file name, restart or logout after the failure.
Edit Keyboard key Mapping under Ubuntu