getpgidsomepid

Getpgidsomepid is not a standard, widely published function name. It is a descriptive term for the operation of obtaining the process group ID (PGID) of a process identified by a given process ID (PID). In standard POSIX interfaces, this operation is performed by the function getpgid(pid_t pid).

Prototype and behavior: The standard form is pid_t getpgid(pid_t pid); If pid is 0, the call returns the PGID of the calling process. If the process identified by pid does not exist, getpgid returns -1 and sets errno to ESRCH. If the pid value is invalid for the implementation, errno may be set to EINVAL. On success, the function returns the process group ID as a non-negative value.

Usage and rationale: Retrieving a process’s PGID is useful for signaling a whole process group, coordinating related processes, and implementing basic job control or process management logic. The PGID indicates which group a process belongs to, which can be used with signals or with tools that operate on groups rather than individual processes.

Example (C):

#include <unistd.h>

#include <stdio.h>

#include <errno.h>

pid_t pid = 1234;

pid_t pgid = getpgid(pid);

if (pgid == -1) {

perror("getpgid");

} else {

printf("PGID of %d is %d\n", pid, pgid);

}

Platform considerations: getpgid is available on most Unix-like systems, including Linux and BSD variants, as well as macOS. Windows does not provide a direct getpgid equivalent; similar functionality may require different APIs such as Job Objects or custom process grouping.

Related terms: getpgid, setpgid, kill, signal handling. See also process groups and job control facilities in POSIX.