SIGINFO
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It has been suggested that this article or section be merged into Unix signal . (Discuss) Proposed since January 2012. |
| Description | status request from the keyboard |
|---|---|
| Default action | ignore |
| SA_SIGINFO macros | |
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On some Unix-like platforms, SIGINFO is the signal sent to computer programs when a status request is received from the keyboard. The symbolic constant for SIGINFO is defined in the header file signal.h.[1] Symbolic signal names are used because signal numbers can vary across platforms.
As SIGINFO is not defined by the POSIX standard, its availability and meaning can vary from system to system. It is most commonly found on BSD-like operating systems.
Most Linux systems do not define SIGINFO and on those that do the meaning is not consistent between different Linux platforms. For example on some versions of Linux, SIGINFO is defined as a synonym for SIGPWR.[2]
[edit] Usage
By default SIGINFO is mapped to the control-t key sequence on the keyboard. This can be changed via "stty status ..."
When the status key is typed on a tty, by default the kernel will print the current load average, active process on that tty and how much cpu it has used since launch. A program may also catch the signal to print additional information, for example dd prints the number of bytes copied so far.
[edit] Etymology
SIG is a common prefix for signal names. INFO is an abbreviation for information request.
[edit] References
- ^ "termios man page". FreeBSD. http://www.freebsd.org/cgi/man.cgi?query=termios&sektion=4. Retrieved January 04, 2012.
- ^ : List of available signals – Linux Conventions and Miscellany Manual
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