setpgrp - Man Page

set the process group ID


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 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.

Return Value

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


No errors are defined.

The following sections are informative.



Application Usage

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.



Future Directions

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

See Also

exec, fork(), getpid(), getsid(), kill(), setpgid(), setsid()

The Base Definitions volume of POSIX.1-2017, <unistd.h>

Referenced By

setsid(3p), unistd.h(0p).

2017 IEEE/The Open Group POSIX Programmer's Manual