getpgid - get the process group ID for a process
#include <unistd.h> pid_t getpgid(pid_t pid);
The getpgid() function returns the process group ID of the process whose process ID is equal to pid. If pid is equal to 0, getpgid() returns the process group ID of the calling process.
Upon successful completion, getpgid() returns a process group ID. Otherwise, it returns (pid_t)-1 and sets errno to indicate the error.
The getpgid() function will fail if:
- The process whose process ID is equal to pid is not in the same session as the calling process, and the implementation does not allow access to the process group ID of that process from the calling process.
- There is no process with a process ID equal to pid.
The getpgid() function may fail if:
- The value of the pid argument is invalid.
exec, fork(), getpgrp(), getpid(), getsid(), setpgid(), setsid(), <unistd.h>.