-.\" Hey Emacs! This file is -*- nroff -*- source.
-.\"
.\" Copyright 1995 James R. Van Zandt <jrv@vanzandt.mv.com>
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
.\"
.\" Changed Tue Sep 19 01:49:29 1995, aeb: moved from man2 to man3
.\" added ref to /etc/utmp, added BUGS section, etc.
.\" modified 2003 Walter Harms, aeb - added getlogin_r, note on stdin use
-.TH GETLOGIN 3 2008-06-29 "GNU" "Linux Programmer's Manual"
+.TH GETLOGIN 3 2013-04-19 "GNU" "Linux Programmer's Manual"
.SH NAME
getlogin, getlogin_r, cuserid \- get username
.SH SYNOPSIS
.BR getlogin ()
returns a pointer to a string containing the name of
the user logged in on the controlling terminal of the process, or a
-NULL pointer if this information cannot be determined.
+null pointer if this information cannot be determined.
The string is
statically allocated and might be overwritten on subsequent calls to
this function or to
returns a pointer to a string containing a username
associated with the effective user ID of the process.
If \fIstring\fP
-is not a NULL pointer, it should be an array that can hold at least
+is not a null pointer, it should be an array that can hold at least
\fBL_cuserid\fP characters; the string is returned in this array.
Otherwise, a pointer to a string in a static area is returned.
This
\fBLOGNAME\fP to find out who the user is.
This is more flexible
precisely because the user can set \fBLOGNAME\fP arbitrarily.
-.SH "RETURN VALUE"
+.SH RETURN VALUE
.BR getlogin ()
returns a pointer to the username when successful,
-and NULL on failure.
+and NULL on failure, with
+.I errno
+set to indicate the cause of the error.
.BR getlogin_r ()
returns 0 when successful, and nonzero on failure.
.SH ERRORS
The system already has the maximum allowed number of open files.
.TP
.B ENXIO
-The calling process has no controlling tty.
+The calling process has no controlling terminal.
.TP
.B ERANGE
(getlogin_r)
-The length of the username, including the terminating null byte,
+The length of the username, including the terminating null byte (\(aq\\0\(aq),
is larger than
.IR bufsize .
.LP
\fI/var/run/utmp\fP
(traditionally \fI/etc/utmp\fP;
some libc versions used \fI/var/adm/utmp\fP)
-.SH "CONFORMING TO"
+.SH ATTRIBUTES
+.SS Multithreading (see pthreads(7))
+The
+.BR getlogin ()
+function is not thread-safe.
+.LP
+The
+.BR getlogin_r ()
+function is thread-safe.
+.LP
+The
+.BR cuserid ()
+function is thread-safe with exceptions.
+It is not thread-safe if called with a NULL parameter.
+.SH CONFORMING TO
.BR getlogin ()
and
.BR getlogin_r ()
and
.BR setlogin (),
and a username
-associated with a session, even if it has no controlling tty.
+associated with a session, even if it has no controlling terminal.
.SH BUGS
Unfortunately, it is often rather easy to fool
.BR getlogin ().
the utmp file.
Often, it gives only the first 8 characters of
the login name.
-The user currently logged in on the controlling tty
+The user currently logged in on the controlling terminal
of our program need not be the user who started it.
Avoid
.BR getlogin ()
what you meant.
.B Do not use
.BR cuserid ().
-.SH "SEE ALSO"
+.SH SEE ALSO
.BR geteuid (2),
.BR getuid (2),
.BR utmp (5)
+.SH COLOPHON
+This page is part of release 3.79 of the Linux
+.I man-pages
+project.
+A description of the project,
+information about reporting bugs,
+and the latest version of this page,
+can be found at
+\%http://www.kernel.org/doc/man\-pages/.
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