1.\" Copyright (c) 1989, 1991 The Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)getlogin.2 6.2 (Berkeley) 03/10/91 7.\" 8.Dd 9.Dt GETLOGIN 2 10.Os BSD 4.2 11.Sh NAME 12.Nm getlogin , 13.Nm setlogin 14.Nd get/set login name 15.Sh SYNOPSIS 16.Fd #include <unistd.h> 17.Ft char * 18.Fn getlogin void 19.Ft int 20.Fn setlogin "const char *name" 21.Sh DESCRIPTION 22The 23.Fn getlogin 24routine 25returns the login name of the user associated with the current session, 26as previously set by 27.Fn setlogin . 28The name is normally associated with a login shell 29at the time a session is created, 30and is inherited by all processes descended from the login shell. 31(This is true even if some of those processes assume another user ID, 32for example when 33.Xr su 1 34is used.) 35.Pp 36.Fn Setlogin 37sets the login name of the user associated with the current session to 38.Fa name . 39This call is restricted to the super-user, and 40is normally used only when a new session is being created on behalf 41of the named user 42(for example, at login time, or when a remote shell is invoked). 43.Sh RETURN VALUES 44If a call to 45.Fn getlogin 46succeeds, it returns a pointer to a null-terminated string in a static buffer. 47If the name has not been set, it returns NULL. 48If a call to 49.Fn setlogin 50succeeds, a value of 0 is returned. If 51.Fn setlogin 52fails, a value of -1 is returned and an error code is 53placed in the global location 54.Va errno . 55.Sh ERRORS 56The following errors may be returned by these calls: 57.Bl -tag -width Er 58.It Bq Er EFAULT 59The 60.Fa name 61parameter gave an 62invalid address. 63.It Bq Er EINVAL 64The 65.Fa name 66parameter 67pointed to a string that was too long. 68Login names are limited to 69.Dv MAXLOGNAME 70(from 71.Ao Pa sys/param.h Ac ) 72characters, currently 12. 73.It Bq Er EPERM 74The caller tried to set the login name and was not the super-user. 75.El 76.Sh SEE ALSO 77.Xr setsid 2 78.Sh BUGS 79Login names are limited in length by 80.Fn setlogin . 81However, lower limits are placed on login names elsewhere in the system 82.Pf ( Dv UT_NAMESIZE 83in 84.Ao Pa utmp.h Ac ) . 85.Pp 86In earlier versions of the system, 87.Fn getlogin 88failed unless the process was associated with a login terminal. 89The current implementation (using 90.Fn setlogin ) 91allows getlogin to succeed even when the process has no controlling terminal. 92In earlier versions of the system, the value returned by 93.Fn getlogin 94could not be trusted without checking the user ID. 95Portable programs should probably still make this check. 96.Sh HISTORY 97The 98.Nm 99function call is currently under development. 100