the operating system using the SIGKILL signal. "Signal excess file size" The SIGXFSZ signal is sent to a process when it grows a file that exceeds the maximum allowed size. "Signal window change" The SIGWINCH signal is sent to a process when its controlling terminal changes its size (a window change). Default action A process can define how to handle incoming POSIX signals. If a process does not define a behaviour for a signal, then the default handler for that signal is being used. The table below lists some default actions for POSIX-compliant UNIX systems, such as FreeBSD, OpenBSD and Linux. Portable number: For most signals the corresponding signal number is implementation-defined. This column lists the numbers specified in the POSIX standard. Actions explained: Terminate Abnormal termination of the process. The process is terminated with all the consequences of _exit() except that the status made available to wait() and waitpid() indicates abnormal termination by the specified signal. Terminate (core dump) Abnormal termination of the process. Additionally, implementation-defined abnormal termination actions, such as creation of a core file, may occur. Ignore Ignore the signal. Stop Stop (or suspend) the process. Continue Continue the process, if it is stopped; otherwise, ignore the signal. Miscellaneous signals The following signals are not specified in the POSIX specification. They are, however, sometimes used on various systems. The SIGEMT signal is sent to a process when an emulator trap occurs. The SIGINFO signal is sent to a process when a status (info) request is received from the controlling terminal. The SIGPWR signal is sent to a process when the system experiences a power failure. The SIGLOST signal is sent to a process when a file lock is lost. The SIGSTKFLT signal is sent to a process when the coprocessor experiences a stack fault (i.e. popping when the stack is empty or pushing when it is full). It is defined by, but not used on Linux, where a x87 coprocessor stack fault will generate SIGFPE instead. The SIGUNUSED signal is sent to a process when a system call with an unused system call number is made. It is synonymous with SIGSYS on most architectures. The SIGCLD signal is synonymous with SIGCHLD. See also C signal handling References External links Unix Signals Table, Ali Alanjawi, University of Pittsburgh Man7.org Signal Man Page Introduction To Unix Signals Programming Another Introduction to Unix Signals Programming (blog post, 2009) UNIX and