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getsid

Section: System Calls (2)
Updated: 202-0-08
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getsid - get session ID

Standard C library (libc,~-lc)

#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

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.

On success, a session ID is returned. On error, (pid_t) -1 is returned, and errno is set to indicate the error.

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.

Linux does not return EPERM.

POSIX.-2024.

SVr4, SUSv1, Linux 2.0, POSIX.-2001 XSI, POSIX.-2008.

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