The kill system call in UNIX Operating System
Introduction
The kill system call is a powerful tool that allows a process to send a signal to another process. This can be used for a variety of purposes, such as terminating a process, pausing a process, or continuing a process.
Syntax
The kill system call takes the following form: ``` int kill(pid_t pid, int sig); ``` where: * `pid` is the process ID of the process to send the signal to. * `sig` is the signal to send.
Signals
Signals are special messages that are sent to processes. There are a variety of different signals, each with its own meaning. Some of the most common signals include: * `SIGINT` (Interrupt): This signal is sent to a process when the user presses the Ctrl+C key combination. * `SIGTERM` (Terminate): This signal is sent to a process when the user presses the Ctrl+\ key combination. * `SIGKILL` (Kill): This signal is sent to a process to terminate it immediately.
Using the kill System Call
The kill system call can be used from the command line or from within a program. To use the kill system call from the command line, use the following syntax: ``` kill -s
``` where: * `` is the signal to send. * `` is the process ID of the process to send the signal to. For example, to send the `SIGINT` signal to a process with a process ID of 1234, you would use the following command: ``` kill -s SIGINT 1234 ``` To use the kill system call from within a program, use the following syntax: ``` int kill(pid_t pid, int sig); ``` where: * `pid` is the process ID of the process to send the signal to. * `sig` is the signal to send. For example, the following C program sends the `SIGINT` signal to a process with a process ID of 1234: ``` #include #include #include int main() { int pid = 1234; int sig = SIGINT; if (kill(pid, sig) == -1) { perror("kill"); exit(EXIT_FAILURE); } return 0; } ```
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