getsid(2) System Calls Manual getsid(2) NAME getsid - get session ID LIBRARY Standard C library (libc, -lc) SYNOPSIS #include <unistd.h> pid_t getsid(pid_t pid); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): getsid(): _XOPEN_SOURCE >= 500 || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L DESCRIPTION getsid() returns the session ID of the process with process ID pid. If pid is 0, getsid() returns the session ID of the calling process. RETURN VALUE On success, a session ID is returned. On error, (pid_t) -1 is returned, and errno is set to indicate the error. ERRORS EPERM A process with process ID pid exists, but it is not in the same session as the calling process, and the implementa‐ tion considers this an error. ESRCH No process with process ID pid was found. VERSIONS This system call is available since Linux 2.0. STANDARDS POSIX.1-2001, POSIX.1-2008, SVr4. NOTES Linux does not return EPERM. See credentials(7) for a description of sessions and session IDs. SEE ALSO getpgid(2), setsid(2), credentials(7) Linux man-pages 6.03 2022-12-04 getsid(2)