Use commands to view a list of supported signals for Linux

We run the following command to see a list of the Linux supported signals:

$ kill-l1) Sighup        2) SIGINT        3) sigquit       4) Sigill 5) Sigtra P       6 SIGABRT       7) Sigbus        8) SIGFPE 9) SIGKILL   &N Bsp  10) SIGUSR1      11) SIGSEGV      12) SIGUSR213 sigpipe      14) Sigal RM      15) sigterm      17) SIGCHLD18) sigcont      19) SIGSTOP   &NBSP ;  20) SIGTSTP      21) SIGTTIN22 Sigttou      23) Sigurg      ) SIGXC PU      25) SIGXFSZ26) sigvtalrm    27) sigprof      28) sigwinch     29 ) SIGIO30) SIGPWR      ) Sigsys      ) sigrtmin     () sigrtmin+136) Sigrtm in+2   Notoginseng) sigrtmin+3   sigrtmin+4  ) sigrtmin+540) sigrtmin+6  ) sigrtmin+7  ) SIGR TmIn+8  ) sigrtmin+944) (sigrtmin+10) sigrtmin+11) sigrtmin+12) sigrtmin+1348) sigrtmin+14 5 0) (SIGRTMAX-14) SIGRTMAX-1352) SIGRTMAX-12) SIGRTMAX-11 SIGRTMAX-10) SIGRTMAX-956) SIGRTMAX-8 TMAX-7  ) SIGRTMAX-6   SIGRTMAX-560) SIGRTMAX-4   SIGRTMAX-3  ) SIGRTMAX-2  ) SI GRTMAX-164) Sigrtmax

In the list, the signal numbered 1 ~ 31 is a traditional UNIX-supported signal that is unreliable (non-real time), and the signal numbered 32 to 63 is later expanded to call it a reliable signal (real-time signal). The difference between unreliable and reliable signals is that the former does not support queuing and may result in loss of signal, which does not.

Below we discuss the signal that the number is less than sigrtmin.

1) sighup

This signal is issued at the end of a user terminal connection (normal or abnormal), usually at the end of the control process of the terminal, notifying each job within the same session, when they are no longer associated with the control terminal.

When you log on to Linux, the system assigns a terminal (session) to the logged-on user. All programs running at this terminal, including foreground process groups and background process groups, are typically part of this session. When the user exits the Linux login, the foreground process group and the background have the process to the terminal output will receive the SIGHUP signal. The default action for this signal is to terminate the process, so the foreground process group and the process with terminal output in the background will be aborted. However, this signal can be captured, such as wget can capture the sighup signal, and ignore it, so that even if you quit the Linux login, wget can continue to download.

In addition, for daemons that are detached from the terminal, this signal is used to notify it to re-read the configuration file.

2) SIGINT

A program termination (interrupt) signal that is issued when the user types a intr character (usually ctrl-c) that notifies the foreground process group to terminate the process.

3) Sigquit

Similar to SIGINT, but controlled by quit characters (usually ctrl-\). A process produces a core file when it exits Sigquit, in the sense that it is similar to a program error signal.

4) Sigill

Illegal directives were executed. Typically, an error occurs in the executable itself, or an attempt is made to execute a data segment. This signal can also be generated when the stack overflows.

5) Sigtrap

Generated by a breakpoint instruction or other trap instruction. Used by debugger.

6) SIGABRT

Call the signal generated by the abort function.

7) Sigbus

Illegal address, including memory address alignment (alignment) error. For example, a four-word integer is accessed, but its address is not a multiple of 4. It differs from SIGSEGV in that the latter is triggered by illegal access to legitimate storage addresses (such as access that is not part of its own storage space or read-only storage).

8) SIGFPE

Emitted when a fatal arithmetic operation error occurs. This includes not only floating-point arithmetic errors, but also all other arithmetic errors such as overflow and divisor 0.

9) SIGKILL

Used to immediately end a program's operation. This signal cannot be blocked, processed, or ignored. If an administrator discovers that a process cannot be terminated, try sending the signal.