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931b8415 | 1 | .\" Copyright (c) 1989, 1991 The Regents of the University of California. |
1cde5d8e KF |
2 | .\" All rights reserved. |
3 | .\" | |
d79c3924 | 4 | .\" %sccs.include.redist.man% |
1cde5d8e | 5 | .\" |
931b8415 | 6 | .\" @(#)getlogin.2 6.2 (Berkeley) %G% |
1cde5d8e | 7 | .\" |
931b8415 CL |
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 | |
d79c3924 | 22 | The |
931b8415 | 23 | .Fn getlogin |
d79c3924 MK |
24 | routine |
25 | returns the login name of the user associated with the current session, | |
26 | as previously set by | |
931b8415 | 27 | .Fn setlogin . |
d79c3924 MK |
28 | The name is normally associated with a login shell |
29 | at the time a session is created, | |
30 | and is inherited by all processes descended from the login shell. | |
31 | (This is true even if some of those processes assume another user ID, | |
32 | for example when | |
931b8415 | 33 | .Xr su 1 |
d79c3924 | 34 | is used.) |
931b8415 CL |
35 | .Pp |
36 | .Fn Setlogin | |
d79c3924 | 37 | sets the login name of the user associated with the current session to |
931b8415 | 38 | .Fa name . |
d79c3924 MK |
39 | This call is restricted to the super-user, and |
40 | is normally used only when a new session is being created on behalf | |
41 | of the named user | |
42 | (for example, at login time, or when a remote shell is invoked). | |
931b8415 | 43 | .Sh RETURN VALUES |
d79c3924 | 44 | If a call to |
931b8415 | 45 | .Fn getlogin |
d79c3924 MK |
46 | succeeds, it returns a pointer to a null-terminated string in a static buffer. |
47 | If the name has not been set, it returns NULL. | |
48 | If a call to | |
931b8415 | 49 | .Fn setlogin |
d79c3924 | 50 | succeeds, a value of 0 is returned. If |
931b8415 CL |
51 | .Fn setlogin |
52 | fails, a value of -1 is returned and an error code is | |
53 | placed in the global location | |
54 | .Va errno . | |
55 | .Sh ERRORS | |
1cde5d8e | 56 | The following errors may be returned by these calls: |
931b8415 CL |
57 | .Bl -tag -width Er |
58 | .It Bq Er EFAULT | |
59 | The | |
60 | .Fa name | |
61 | parameter gave an | |
1cde5d8e | 62 | invalid address. |
931b8415 CL |
63 | .It Bq Er EINVAL |
64 | The | |
65 | .Fa name | |
66 | parameter | |
d79c3924 | 67 | pointed to a string that was too long. |
931b8415 CL |
68 | Login names are limited to |
69 | .Dv MAXLOGNAME | |
70 | (from | |
71 | .Ao Pa sys/param.h Ac ) | |
d79c3924 | 72 | characters, currently 12. |
931b8415 | 73 | .It Bq Er EPERM |
d79c3924 | 74 | The caller tried to set the login name and was not the super-user. |
931b8415 CL |
75 | .El |
76 | .Sh SEE ALSO | |
77 | .Xr setsid 2 | |
78 | .Sh BUGS | |
d79c3924 | 79 | Login names are limited in length by |
931b8415 | 80 | .Fn setlogin . |
d79c3924 | 81 | However, lower limits are placed on login names elsewhere in the system |
931b8415 CL |
82 | .Pf ( Dv UT_NAMESIZE |
83 | in | |
84 | .Ao Pa utmp.h Ac ) . | |
85 | .Pp | |
d79c3924 | 86 | In earlier versions of the system, |
931b8415 | 87 | .Fn getlogin |
d79c3924 MK |
88 | failed unless the process was associated with a login terminal. |
89 | The current implementation (using | |
931b8415 | 90 | .Fn setlogin ) |
d79c3924 MK |
91 | allows getlogin to succeed even when the process has no controlling terminal. |
92 | In earlier versions of the system, the value returned by | |
931b8415 | 93 | .Fn getlogin |
d79c3924 MK |
94 | could not be trusted without checking the user ID. |
95 | Portable programs should probably still make this check. | |
931b8415 CL |
96 | .Sh HISTORY |
97 | The | |
98 | .Nm | |
99 | function call is currently under development. |