getsid − get session ID

#include <unistd.h>

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 session leader.) On error, (pid_t) −1 will be returned, and errno is set appropriately.

EPERM

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.

ESRCH

No process with process ID p was found.

SVr4, POSIX 1003.1-2001.

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.

getpgid(2), setsid(2)