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| .TH TCGETSID 3 2021-03-22 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| tcgetsid \- get session ID |
| .SH SYNOPSIS |
| .nf |
| .BR "#define _XOPEN_SOURCE 500" " /* See feature_test_macros(7) */" |
| .B "#include <termios.h>" |
| .PP |
| .BI "pid_t tcgetsid(int " fd ); |
| .fi |
| .SH DESCRIPTION |
| The function |
| .BR tcgetsid () |
| returns the session ID of the current session that has the |
| terminal associated to |
| .I fd |
| as controlling terminal. |
| This terminal must be the controlling terminal of the calling process. |
| .SH RETURN VALUE |
| When |
| .I fd |
| refers to the controlling terminal of our session, |
| the function |
| .BR tcgetsid () |
| will return the session ID of this session. |
| Otherwise, \-1 is returned, and |
| .I errno |
| is set to indicate the error. |
| .SH ERRORS |
| .TP |
| .B EBADF |
| .I fd |
| is not a valid file descriptor. |
| .TP |
| .B ENOTTY |
| The calling process does not have a controlling terminal, or |
| it has one but it is not described by |
| .IR fd . |
| .SH VERSIONS |
| .BR tcgetsid () |
| is provided in glibc since version 2.1. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR tcgetsid () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008. |
| .SH NOTES |
| This function is implemented via the |
| .B TIOCGSID |
| .BR ioctl (2), |
| present |
| since Linux 2.1.71. |
| .SH SEE ALSO |
| .BR getsid (2) |
