Signals are a way to interact with processes in linux.

Each signal has one of five default actions a process will take when it receives the signal. These can be:

• Term → Terminate the running process.
• Ign → Ignore the signal.
• Core → Terminate the process and dump core.
• Stop → Stop the process.
• Cont → Continue process if stopped.

These are called dispositions. It’s what a process does when it receives a signal and, for some signals, they can be changed (with the signal syscall)
Some signals cannot be ignored (they can’t have their disposition changed), like … which signals??

You can send all kind of signals with kill! It’s really useful for terminating processes, debugging and just messing with weird signals.

Some really useful signals:

NOTE: Signal numbering on different architectures Many signals have different numeric values on different architectures (MIPS, for example). Consult the manpage on a full list.

Complete with info from manpage and bite size linux.