SETPGRP(3P) POSIX Programmer's Manual SETPGRP(3P)

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.

setpgrp — set the process group ID

#include <unistd.h>
pid_t setpgrp(void);

If the calling process is not already a session leader, setpgrp() sets the process group ID of the calling process to the process ID of the calling process. If setpgrp() creates a new session, then the new session has no controlling terminal.

The setpgrp() function has no effect when the calling process is a session leader.

Upon completion, setpgrp() shall return the process group ID.

No errors are defined.

The following sections are informative.


It is unspecified whether this function behaves as setpgid(0,0) or setsid() unless the process is already a session leader. Therefore, applications are encouraged to use setpgid() or setsid() as appropriate.


The setpgrp() function may be removed in a future version.

exec, fork(), getpid(), getsid(), kill(), 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 .

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2017 IEEE/The Open Group