#### 25.2.7 Miscellaneous Signals ¶

These signals are used for various other purposes. In general, they will not affect your program unless it explicitly uses them for something.

Macro: `int` SIGUSR1 ¶
Macro: `int` SIGUSR2 ¶

  The `SIGUSR1` and `SIGUSR2` signals are set aside for you to use any way you want. They’re useful for simple interprocess communication, if you write a signal handler for them in the program that receives the signal.

  There is an example showing the use of `SIGUSR1` and `SIGUSR2` in Signaling Another Process.

  The default action is to terminate the process.

Macro: `int` SIGWINCH ¶

  Window size change. This is generated on some systems (including GNU) when the terminal driver’s record of the number of rows and columns on the screen is changed. The default action is to ignore it.

  If a program does full-screen display, it should handle `SIGWINCH`. When the signal arrives, it should fetch the new screen size and reformat its display accordingly.

  This macro was originally a BSD extension, but was added in POSIX.1-2024.

Macro: `int` SIGINFO ¶

  Information request. On 4.4 BSD and GNU/Hurd systems, this signal is sent to all the processes in the foreground process group of the controlling terminal when the user types the STATUS character in canonical mode; see Characters that Cause Signals.

  If the process is the leader of the process group, the default action is to print some status information about the system and what the process is doing. Otherwise the default is to do nothing.

Macro: `int` SIGPWR ¶

  Power lost or restored. On s390x Linux systems, this signal is generated when a machine check warning is issued, and is sent to the process designated to receive ctrl-alt-del notifications. Otherwise, it is up to userspace applications to generate this signal and manage notifications as to the type of power event that happened.

  The default action is to terminate the process.