TCGETSID(3)                                                             Linux Programmer's Manual                                                            TCGETSID(3)

NAME
       tcgetsid - get session ID

SYNOPSIS
       #define _XOPEN_SOURCE 500        /* See feature_test_macros(7) */
       #include <termios.h>

       pid_t tcgetsid(int fd);

DESCRIPTION
       The  function tcgetsid() returns the session ID of the current session that has the terminal associated to fd as controlling terminal.  This terminal must be the
       controlling terminal of the calling process.

RETURN VALUE
       When fd refers to the controlling terminal of our session, the function tcgetsid() will return the session ID of this session.  Otherwise, -1  is  returned,  and
       errno is set to indicate the error.

ERRORS
       EBADF  fd is not a valid file descriptor.

       ENOTTY The calling process does not have a controlling terminal, or it has one but it is not described by fd.

VERSIONS
       tcgetsid() is provided in glibc since version 2.1.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                                                                                             │ Attribute     │ Value   │
       ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │tcgetsid()                                                                                                                            │ Thread safety │ MT-Safe │
       └──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

NOTES
       This function is implemented via the TIOCGSID ioctl(2), present since Linux 2.1.71.

SEE ALSO
       getsid(2)

GNU                                                                            2021-03-22                                                                    TCGETSID(3)