SIGUSR1 and SIGUSR2

SIGUSR1 and SIGUSR2

Infobox Computing signal
description = User-defined signals
action = Abnormal termination of the processOn POSIX-compliant platforms, SIGUSR1 and SIGUSR2 are signals sent to computer programs to indicate user-defined conditions. The symbolic constants for them are defined in the header file signal.h. Symbolic signal names are used because signal numbers can vary across platforms.

Etymology

"SIG" is a common prefix for signal names. "USR" is an abbreviation for "user-defined".

Usage

Along with the realtime signals SIGRTMIN through SIGRTMAX, the semantics of SIGUSR1 and SIGUSR2 are not specified by POSIX. Use varies widely from one application to another.

Many applications use USR1 to synchronize internal data between threads and processes, for example by the obsolete LinuxThreads threading library under Linux 2.0 (superseded by the Native POSIX Thread Library). Other applications, such as dd, will print status when given this signal. USR1 is also often used to tell an application to reload config files; for example, sending the Apache HTTP Server a USR1, will ask the server send to stop allowing new connections, wait for the current ones to die, reread the config files, and restart the server, allowing for relatively smooth in-production changes.

ee also

* [http://pauillac.inria.fr/~xleroy/linuxthreads/faq.html#H.4 LinuxThreads and SIGUSR1/SIGUSR2]


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • SIGHUP — Infobox Computing signal description = Hangup action = Abnormal termination of the processSIGHUP is a signal used on POSIX compliant platforms, originally designed to notify processes of a serial line drop. SIGHUP is a symbolic constant defined… …   Wikipedia

  • LinuxThreads — In the Linux operating system, LinuxThreads was a partial implementation of POSIX Threads that has since been superseded by the Native POSIX Thread Library (NPTL).LinuxThreads had a number of problems, mainly owing to the implementation, which… …   Wikipedia

  • Señal (informática) — Una señal (signal) es una forma limitada de comunicación entre procesos empleada en Unix y otros sistemas operativos compatibles con POSIX. En esencia es una notificación asíncrona enviada a un proceso para informarle de un evento. Cuando se le… …   Wikipedia Español

  • Signal (computing) — A signal is a limited form of inter process communication used in Unix, Unix like, and other POSIX compliant operating systems. Essentially it is an asynchronous notification sent to a process in order to notify it of an event that occurred. When …   Wikipedia

  • signal.h — Esta página o sección está siendo traducida, razón por la cual puede haber lagunas de contenidos, errores sintácticos o escritos sin traducir. Puedes colaborar con Wikipedia continuando con la traducción desde el artículo original. signal.h es un …   Wikipedia Español

  • Сигналы (UNIX) — У этого термина существуют и другие значения, см. Сигнал (значения). Сигналы в UNIX, Unix подобных и других POSIX совместимых операционных системах являются одним из способов взаимодействия между процессами (англ. IPC, inter process… …   Википедия

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”