Overview

• This is chapter 20, you should read it.
• A signal is a notification to a process that an event has occured.
  • It is equivelent to a hardware interrupt.
  • The flow of execution is inturrupted.
  • A function is executed
  • Flow is returend to the point of inturruption.
• There is no way to know where/when this will occur.
• Types of things that cause a process to recieve a signal
  • Hardware exception
    • Division by 0
    • Executing an illegal instruction.
    • Dereferencing a bad pointer.
  • User interaction
    • ctrl-c, z,
  • Software event
    • input is available
    • cpu time lmit exceeded
    • A child process exeted.
• Signals are
  • Small integers, starting at 1.
  • And a corresponding symbolic name. (SIGxxxxx)
  • This differs from system to system so memorizing these numbers is useless.
  • See man 7 signal
• Notes by hand, sorry.