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SETPGID(2) NetBSD System Calls Manual SETPGID(2)
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setpgid, setpgrp -- set process group
Standard C Library (libc, -lc)
setpgid(pid_t pid, pid_t pgrp);
setpgrp(pid_t pid, pid_t pgrp);
setpgid() sets the process group of the specified process pid to the
specified pgrp. If pid is zero, then the call applies to the current
process. If pgrp is zero, then the process id of the process specified
by pid is used instead.
If the invoker is not the super-user, then the affected process must have
the same effective user-id as the invoker or be a descendant of the
In general to set the process group of a newly forked subprocess, both
the child and parent processes should call setpgid() to ensure that the
process group change takes effect in a timely fashion. One call will
succeed and the other will fail, depending on process scheduling.
setpgid() returns 0 when the operation was successful. If the request
failed, -1 is returned and the global variable errno indicates the rea-
setpgrp() is identical to setpgid(), and is retained for calling conven-
tion compatibility with historical versions of BSD.
setpgid() will fail and the process group will not be altered if:
[EACCES] The value of the pid argument matches the process ID
of a child process of the calling process, and the
child process has successfully executed one of the
[EINVAL] The value of the pgrp argument is less than zero.
[EPERM] The effective user ID of the requested process is dif-
ferent from that of the caller and the process is not
a descendant of the calling process.
[ESRCH] The value of the pid argument does not match the
process ID of the calling process or of a child
process of the calling process.
The setpgid() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').
NetBSD 10.99 March 15, 2022 NetBSD 10.99