As mentioned in the previous chapter, signals are a crucial mechanism for the Linux system developer to understand and exploit. The previous chapter covered several areas: an introduction, why signaling is useful to the systems developer, and, most importantly, how exactly the developer is to handle and thus exploit the signaling mechanism.

This chapter continues this exploration. Here, we will drill down into the inner details of process crash handling with signaling, how to recognize and avoid common issues when dealing with signals, working with real-time signals, sending signals, and finally, alternative means of performing signal handling.

In this chapter, the reader will learn the following:

• Gracefully handling process crashes, and collecting valuable diagnostics at that point
• Handling common gotchas to do with signaling—errno races, the correct way to sleep (yes, you read that right!)
• Handling powerful real-time signals
• Sending signals to other processes, and performing IPC via signals
• Alternative signal-handling techniques