Unix for Beginners
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getsid() - Unix, Linux System Call
getsid - get session ID
pid_t getsid(pid_t pid);
getsid(0) returns the session ID of the calling process.
getsid(p) returns the session ID of the process with process ID
p. (The session ID of a process is the process group ID of the
On error, (pid_t) -1 will be returned, and
errno is set appropriately.
A process with process ID
p exists, but it is not in the same session as the current process,
and the implementation considers this an error.
No process with process ID
p was found.
Linux does not return EPERM.
Linux has this system call since Linux 1.3.44.
There is libc support since libc 5.2.19.
To get the prototype under glibc, define both _XOPEN_SOURCE and
_XOPEN_SOURCE_EXTENDED, or use "#define _XOPEN_SOURCE n"
for some integer n larger than or equal to 500.