router(config)#configuration mode exclusive
  auto    Lock configuration mode automatically
  manual  Lock configuration mode on-demand
router(config)#configuration mode exclusive manual
router(config)#exit
router#configuration terminal lock
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#do show configuration lock
Parser Configure Lock
---------------------
Owner PID        : 167
User             : iman
TTY              : 322
Type             : EXCLUSIVE
State            : LOCKED
Class            : EXPOSED
Count            : 1
Pending Requests : 0
User debug info  : configure terminal lock

router#conf t
Configuration mode locked exclusively by user 'iman' process '167' from term
inal '322'. Please try later.