    Signals


Processes can send and receive signals from themselves, other processes and 
from the kernel. When a signal is received by a process, it tries to trigger
an interrupt that has the index number of the signal. If no interrupt handler
is specified for that interrupt vector, the default action of the signal is
performed. For example, SIGTERM kills the process if the process does not have
an interrupt handler for interrupt 15.

Signals can have values only from 1 to 255. The interrupt table itself can be
2^16 entries long, so interrupts over 255 cannot conflict with any of the
signals.
    
  1. Signal table
  
See SIGDEF.C.


  2. Non-POSIX signals:
  
Signal 128 (SIGHIDECON) hides the console window.
Signal 129 (SIGSHOWCON) shows the console window.