getsid(2) System Calls Manual getsid(2) getsid - (libc -lc) #include pid_t getsid(pid_t pid); glibc ( feature_test_macros(7)): getsid(): _XOPEN_SOURCE >= 500 || /* glibc 2.12: */ _POSIX_C_SOURCE >= 200809L getsid() pid. pid 0 getsid() . . (pid_t) -1 errno . EPERM pid . ESRCH pid. EPERM. POSIX.1-2024. SVr4 SUSv1 2.0 POSIX.1-2001 XSI POSIX.1-2008. credentials(7) . getpgid(2) setsid(2) credentials(7) 3 . . : . 6.18 8 2026 getsid(2)