This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
#include <unistd.h> pid_t getpgid(pid_t pid);
The getpgid() function shall return the process group ID of the process whose process ID is equal to pid. If pid is equal to 0, getpgid() shall return the process group ID of the calling process.
Upon successful completion, getpgid() shall return a process group ID. Otherwise, it shall return (pid_t)-1 and set errno to indicate the error.
The getpgid() function shall 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.
The following sections are informative.
exec, fork(), getpgrp(), getpid(), getsid(), setpgid(), setsid()
The Base Definitions volume of POSIX.1-2017, <unistd.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .
getpgrp(3p), getppid(3p), getsid(3p), killpg(3p), unistd.h(0p).