2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
208 lines
5.7 KiB
Groff
208 lines
5.7 KiB
Groff
.\" $NetBSD: getlogin.2,v 1.22 2009/01/11 02:46:30 christos Exp $
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.\"
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.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getlogin.2 8.1 (Berkeley) 6/9/93
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.\"
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.Dd January 6, 2009
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.Dt GETLOGIN 2
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.Os
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.Sh NAME
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.Nm getlogin ,
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.Nm getlogin_r ,
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.Nm setlogin
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.Nd get/set login name
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft char *
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.Fn getlogin void
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.Ft int
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.Fn getlogin_r "char *name" "size_t len"
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.Ft int
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.Fn setlogin "const char *name"
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.Sh DESCRIPTION
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The
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.Fn getlogin
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routine
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returns the login name of the user associated with the current session,
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as previously set by
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.Fn setlogin .
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The name is normally associated with a login shell
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at the time a session is created,
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and is inherited by all processes descended from the login shell.
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(This is true even if some of those processes assume another user ID,
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for example when
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.Xr su 1
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is used.)
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.Pp
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The
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.Fn getlogin_r
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function
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provides the same service as
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.Fn getlogin ,
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however the caller must provide the buffer
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.Fa name
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with length
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.Fa len
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bytes
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to hold the result.
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The buffer should be at least
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.Dv MAXLOGNAME
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bytes in length.
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.Pp
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.Fn setlogin
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sets the login name of the user associated with the current session to
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.Fa name .
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This call is restricted to the super-user, and
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is normally used only when a new session is being created on behalf
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of the named user
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(for example, at login time, or when a remote shell is invoked).
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.Pp
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.Em NOTE :
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There is only one login name per session.
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.Pp
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It is
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.Em CRITICALLY
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important to ensure that
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.Fn setlogin
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is only ever called after the process has taken adequate steps to ensure
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that it is detached from its parent's session.
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The
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.Em ONLY
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way to do this is via the
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.Fn setsid
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function.
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The
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.Fn daemon
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function calls
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.Fn setsid
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which is an ideal way of detaching from a controlling terminal and
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forking into the background.
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.Pp
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In particular, neither
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.Fn ioctl ttyfd TIOCNOTTY ...
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nor
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.Fn setpgid ...
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is sufficient to create a new session.
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.Pp
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Once a parent process has called
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.Fn setsid ,
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it is acceptable for some child of that process to then call
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.Fn setlogin ,
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even though it is not the session leader.
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Beware, however, that
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.Em ALL
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processes in the session will change their login name at the same time,
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even the parent.
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.Pp
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This is different from traditional
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.Ux
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privilege inheritance and as such can be counter-intuitive.
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.Pp
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Since the
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.Fn setlogin
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routine is restricted to the super-user, it is assumed that (like
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all other privileged programs) the programmer has taken adequate
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precautions to prevent security violations.
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.Sh RETURN VALUES
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If a call to
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.Fn getlogin
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succeeds, it returns a pointer to a null-terminated string in a static buffer.
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If the name has not been set, it returns
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.Dv NULL .
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.Pp
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If a call to
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.Fn setlogin
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succeeds, a value of 0 is returned.
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If
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.Fn setlogin
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fails, a value of \-1 is returned and an error code is
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placed in the global location
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.Va errno .
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.Pp
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The
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.Fn getlogin_r
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function
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returns zero if successful, or the error number upon failure.
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.Sh ERRORS
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The following errors may be returned by these calls:
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.Bl -tag -width Er
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.It Bq Er EFAULT
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The
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.Fa name
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parameter gave an
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invalid address.
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.It Bq Er EINVAL
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The
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.Fa name
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parameter
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pointed to a string that was too long.
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Login names are limited to
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.Dv MAXLOGNAME
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(from
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.Ao Pa sys/param.h Ac )
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characters, currently 16.
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.It Bq Er EPERM
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The caller tried to set the login name and was not the super-user.
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.It Bq Er ERANGE
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The size of the buffer is smaller than the result to be returned.
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.El
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.Sh SEE ALSO
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.Xr setsid 2
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.Sh STANDARDS
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The
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.Fn getlogin
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and
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.Fn getlogin_r
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functions conform to
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.St -p1003.1-96 .
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.Sh HISTORY
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The
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.Fn getlogin
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function first appeared in
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.Bx 4.4 .
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.Sh BUGS
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Login names are limited in length by
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.Fn setlogin .
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However, lower limits are placed on login names elsewhere in the system
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.Pf ( Dv UT_NAMESIZE
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in
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.Ao Pa utmp.h Ac ) .
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.Pp
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In earlier versions of the system,
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.Fn getlogin
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failed unless the process was associated with a login terminal.
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The current implementation (using
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.Fn setlogin )
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allows getlogin to succeed even when the process has no controlling terminal.
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In earlier versions of the system, the value returned by
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.Fn getlogin
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could not be trusted without checking the user ID.
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Portable programs should probably still make this check.
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