Signal signal specific meaning explanation ~

1SIGHUP This signal is issued at the end of the user terminal connection (normal or abnormal), usually at the end of the control process of the terminal to notify the same session of the various jobs, when they are no longer associated with the control terminal.2) SIGINT program termination (interrupt) signal, usually from terminal interrupt command such as CTRL +C or DELETE key3Sigquit and SIGINT are similar, but by the quit character (usually Ctrl +\) to control. The process generates a core file when it receives a sigquit exit, similar to a program error signal in this sense.4Sigill executed an illegal instruction. Typically, the executable file itself has an error, or an attempt is made to execute a data segment. This signal can also be generated when a stack overflows.5SIGTRAP Tracks trap signals, generated by breakpoint commands or other trap instructions. Used by debugger.6SIGABRT the signal generated when the abort is called will cause the process to end abnormally. 6) Sigiot IO error signal.7Sigbus the signal generated by the system bus error, an illegal address, including memory address alignment (alignment) error. Eg: accesses a four-word integer, but its address is not a multiple of 4.8SIGFPE is emitted when a fatal arithmetic operation error occurs. It includes not only floating-point arithmetic errors, but also overflow and all other arithmetic errors such as divisor 0.9SIGKILL can terminate signals from any process, which can only be issued by an administrator, and the signal will not be captured or ignored. TenSIGUSR1 is left to the user, and the user can define it in the application itself.  OneSIGSEGV attempts to access memory that is not allocated to itself, or attempts to write data to a memory address that does not have write permissions, illegally using a memory address signal.  A) SIGUSR2 left to the user to use -Sigpipe the signal that is generated when a process finishes reading a pipeline.  -) a SIGALRM clock timing signal, which is signaled when the time set by the alarm function terminates.  theSIGTERM program End (terminate) signal, unlike Sigkill, the signal can be blocked and processed. Usually used to ask the program to exit normally. The shell command kill generates this signal by default . -SIGCHLD The signal is generated when the child process ends or is interrupted, the parent process receives the signal. The parent process of the signal can know the health of the child process. But in most cases this signal is ignored.  -Sigcont let a Stop (stopped) process continue execution. This signal cannot be blocked. +SIGSTOP The execution of the Stop (stopped) process. Note the difference between it and terminate and interrupt: The process is not finished yet, just pausing execution. This signal cannot be blocked, processed or ignored. -SIGTSTP stops the process, but the signal can be processed and ignored. When a user types a susp character (usually ctrl-Z) Send this signal +Sigttin interrupt the signal generated by the drive when the background job is to read data from the user terminal. The signal does not occur and a read error occurs when the process that reads the data blocks or ignores the signal, or the process group in which the data is read is an orphaned process group. Errno is set to Eto ASigttou is similar to Sigttin, which interrupts the signal generated by the drive when the background job is to read data from the user terminal. The signal does not occur and a read error occurs when the process that reads the data blocks or ignores the signal, or the process group in which the data is read is an orphaned process group. Errno is set to Eto. The only difference is that the process can choose to write back.  atAn emergency on the Sigurg socket is a message sent.  -SIGXCPU exceeds the CPU time resource limit. This limit can be read by getrlimit/setrlimitChange -) Sigxfsz exceeds the file size resource limit. -) SIGVTALRM virtual clock signal. Similar to SIGALRM, but calculates the CPU time that the process consumes. -) Sigprof similar to sigalrm/SIGVTALRM, but includes the CPU time used by the process and the time of the system call. -sigwinch The window size is changed. in) The SIGIO file descriptor is ready to begin input/output operation. -) SIGPWR power failure supply failure signal.  toSIGEMT a signal generated when a real-time hardware error occurs. There are two signals to stop a process: Sigterm and Sigkill. Sigterm is friendly and the process captures the signal and shuts down the program according to your needs. Before you close the program, you can end the open record file and complete the task you are doing.   In some cases, if the process is working and cannot be interrupted, the process can ignore the sigterm signal. For Sigkill signals, the process cannot be ignored. This is a "I don't care what you are doing, stop immediately" signal.   If you send a sigkill signal to the process, Linux stops the process there. Note: There are six signals called job signals, Sigchld,sigcont,sigstop,sigstp,sigttni,sigttou. These signals are used to coordinate and organize each process, that is, to achieve so-called job control. Typically, the user does not need to process these signals, and the shell automatically completes the processing of these signals. The signals are affected by each other, and when the process receives the sigcont signal, the Sigstop,sigstp,sigttin,sigttou suspended by the system will fail. The Sigcont will fail when the same process receives the Sigstop,sigstp,sigttin,sigttou. 

Signal signal specific meaning explanation ~