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 implementation considers this an error.

ESRCH
    No process with process ID pid was found.

VERSIONS
Linux does not return EPERM.

STANDARDS
POSIX.1-2024.

HISTORY
POSIX.1-2001, SVr4. Linux 2.0.

NOTES
See credentials(7) for a description of sessions and session IDs.

SEE ALSO
getpgid(2), setsid(2), credentials(7)