How to use the kill function in C language

The kill function sends a specified signal to the process, requiring the process ID and signal number. Commonly used signal numbers include SIGHUP (terminal suspension), SIGINT (keyboard interrupt), SIGQUIT (exit), SIGILL (illegal instruction), SIGFPE (floating point exception), and SIGSEGV (illegal memory access). Note that sending signals requires root permissions, and some signals may be blocked or ignored by the process.

C language kill function

Introduction
The kill function is used to send signals to a process. It requires two parameters: the process ID and the signal number.

How to use
int kill(pid_t pid, int sig);

• pid: The process ID to which the signal is to be sent.
• sig: The signal number to be sent.

Return value

• Success: 0
• Failed: -1, and set the errno variable.

Signal number
The following are commonly used signal numbers:

• SIGHUP: Terminal hang
• SIGINT: Keyboard interrupt
• SIGQUIT: Exit
• SIGILL: Illegal Directive
• SIGFPE: Floating point exception
• SIGSEGV: Illegal memory access

Example of usage

Send SIGHUP signal to a process with process ID 12345:

 <code class="c">#include <signal.h> int main() { kill(12345, SIGHUP); return 0; }</signal.h></code>

Things to note

• Root permission is required to send signals.
• Some signals may be blocked or ignored by the process.

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