signalSIGTERM

signalSIGTERM is a software-defined signal used in Unix-like operating systems to request the termination of a running process gracefully. It is one of the standard signals defined in the POSIX standard and is sent to a process to allow it to perform cleanup tasks, such as closing open files, releasing locks, or writing logs before exiting. Unlike forceful termination signals like SIGKILL, SIGTERM does not immediately terminate the process but instead sends it a request to shut down cleanly.

The signal is typically sent using the `kill` command, which can be invoked with the `-s SIGTERM` option or by specifying the signal number directly (e.g., `kill -15`). In modern systems, many applications and scripts automatically handle SIGTERM by implementing a termination handler (often registered via the `signal()` function in C or equivalent mechanisms in other languages). This handler allows the process to perform necessary cleanup operations before exiting with a status code of 0, indicating successful termination.

SIGTERM is commonly used in server environments to manage long-running processes, such as web servers or databases. For example, a web server might receive SIGTERM to shut down gracefully, allowing time for pending requests to complete before the process terminates. If a process does not handle SIGTERM appropriately, it may continue running until it is forcibly terminated by another signal like SIGKILL (signal number 9).

The behavior of SIGTERM can vary slightly between different operating systems and versions of Unix-like systems, but the core functionality remains consistent. It serves as a standard way to request orderly process termination, promoting resource efficiency and minimizing data loss.