1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
|
.\" Copyright 1995 Mark D. Roth (roth@uiuc.edu)
.\"
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" the License, or (at your option) any later version.
.\"
.\" The GNU General Public License's references to "object code"
.\" and "executables" are to be interpreted as the output of any
.\" document formatting or typesetting system, including
.\" intermediate and printed output.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public
.\" License along with this manual; if not, write to the Free
.\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111,
.\" USA.
.\"
.\" References consulted:
.\" Linux libc source code
.\" Solaris manpages
.\"
.\" Modified Thu Jul 25 14:43:46 MET DST 1996 by Michael Haardt <michael@cantor.informatik.rwth-aachen.de>
.\"
.TH GETUTENT 3 1996-07-25 "" "Library functions"
.SH NAME
getutent, getutid, getutline, pututline, setutent, endutent, utmpname \- access utmp file entries
.SH SYNOPSIS
.B #include <utmp.h>
.sp
.B struct utmp *getutent(void);
.br
.BI "struct utmp *getutid(struct utmp *" ut );
.br
.BI "struct utmp *getutline(struct utmp *" ut );
.sp
.BI "struct utmp *pututline(struct utmp *" ut );
.sp
.B void setutent(void);
.br
.B void endutent(void);
.sp
.BI "void utmpname(const char *" file );
.SH DESCRIPTION
.BR utmpname ()
sets the name of the utmp-format file for the other utmp
functions to access.
If
.BR utmpname ()
is not used to set the filename
before the other functions are used, they assume \fB_PATH_UTMP\fP, as
defined in \fI<paths.h>\fP.
.PP
.BR setutent ()
rewinds the file pointer to the beginning of the utmp file.
It is generally a Good Idea to call it before any of the other
functions.
.PP
.BR endutent ()
closes the utmp file.
It should be called when the user
code is done accessing the file with the other functions.
.PP
.BR getutent ()
reads a line from the current file position in the utmp
file.
It returns a pointer to a structure containing the fields of
the line.
.PP
.BR getutid ()
searches forward from the current file position in the utmp
file based upon \fIut\fP.
If \fIut\fP->ut_type is one of \fBRUN_LVL\fP,
\fBBOOT_TIME\fP, \fBNEW_TIME\fP, or \fBOLD_TIME\fP,
.BR getutid ()
will
find the first entry whose \fIut_type\fP field matches \fIut\fP->ut_type.
If \fIut\fP->ut_type is one of \fBINIT_PROCESS\fP, \fBLOGIN_PROCESS\fP,
\fBUSER_PROCESS\fP, or \fBDEAD_PROCESS\fP,
.BR getutid ()
will find the
first entry whose ut_id field matches \fIut\fP->ut_id.
.PP
.BR getutline ()
searches forward from the current file position in the
utmp file.
It scans entries whose ut_type is \fBUSER_PROCESS\fP
or \fBLOGIN_PROCESS\fP and returns the first one whose ut_line field
matches \fIut\fP->ut_line.
.PP
.BR pututline ()
writes the utmp structure \fIut\fP into the utmp file.
It uses
.BR getutid ()
to search for the proper place in the file to insert
the new entry.
If it cannot find an appropriate slot for \fIut\fP,
.BR pututline ()
will append the new entry to the end of the file.
.SH "RETURN VALUE"
.BR getutent (),
.BR getutid (),
.BR getutline ()
and
.BR pututline ()
return a pointer to a \fBstruct utmp\fP on success, and NULL on failure.
This \fBstruct utmp\fP is allocated in static storage, and may be
overwritten by subsequent calls.
.SH "REENTRANT VERSIONS"
These above functions are not thread-safe.
Glibc adds reentrant versions
.sp
.nf
.BR "#define _GNU_SOURCE" " /* or _SVID_SOURCE or _BSD_SOURCE */"
.B #include <utmp.h>
.sp
.BI "int getutent_r(struct utmp *" ubuf ", struct utmp **" ubufp );
.sp
.BI "int getutid_r(struct utmp *" ut ,
.BI " struct utmp *" ubuf ", struct utmp **" ubufp );
.sp
.BI "int getutline_r(struct utmp *" ut ,
.BI " struct utmp *" ubuf ", struct utmp **" ubufp );
.fi
.sp
These functions are GNU extensions, analogs of the functions of the
same name without the _r suffix.
The
.I ubuf
parameter gives these functions a place to store their result.
On success they return 0, and a pointer to the result is written in
.RI * ubufp .
On error these functions return \-1.
.SH EXAMPLE
The following example adds and removes a utmp record, assuming it is run
from within a pseudo terminal.
For usage in a real application, you
should check the return values of
.BR getpwuid (3)
and
.BR ttyname (3).
.PP
.nf
#include <string.h>
#include <stdlib.h>
#include <pwd.h>
#include <unistd.h>
#include <utmp.h>
int
main(int argc, char *argv[])
{
struct utmp entry;
system("echo before adding entry:;who");
entry.ut_type=USER_PROCESS;
entry.ut_pid=getpid();
strcpy(entry.ut_line,ttyname(0)+strlen("/dev/"));
/* only correct for ptys named /dev/tty[pqr][0\-9a\-z] */
strcpy(entry.ut_id,ttyname(0)+strlen("/dev/tty"));
time(&entry.ut_time);
strcpy(entry.ut_user,getpwuid(getuid())\->pw_name);
memset(entry.ut_host,0,UT_HOSTSIZE);
entry.ut_addr=0;
setutent();
pututline(&entry);
system("echo after adding entry:;who");
entry.ut_type=DEAD_PROCESS;
memset(entry.ut_line,0,UT_LINESIZE);
entry.ut_time=0;
memset(entry.ut_user,0,UT_NAMESIZE);
setutent();
pututline(&entry);
system("echo after removing entry:;who");
endutent();
return 0;
}
.fi
.SH FILES
/var/run/utmp database of currently logged-in users
.br
/var/log/wtmp database of past user logins
.SH "CONFORMING TO"
XPG2, SVr4.
.LP
In XPG2 and SVID 2 the function \fIpututline\fP() is documented
to return void, and that is what it does on many systems
(AIX, HP-UX, Linux libc5).
HP-UX introduces a new function \fI_pututline\fP() with the prototype
given above for \fIpututline\fP() (also found in Linux libc5).
.LP
All these functions are obsolete now on non-Linux systems.
POSIX.1-2001, following SUSv1,
does not have any of these functions, but instead uses
.sp
.B #include <utmpx.h>
.sp
.B struct utmpx *getutxent(void);
.br
.B struct utmpx *getutxid(const struct utmpx *);
.br
.B struct utmpx *getutxline(const struct utmpx *);
.br
.B struct utmpx *pututxline(const struct utmpx *);
.br
.B void setutxent(void);
.br
.B void endutxent(void);
.sp
The \fIutmpx\fP structure is a superset of the \fIutmp\fP structure,
with additional fields, and larger versions of the existing fields.
The corresponding files are often
.I /var/*/utmpx
and
.IR /var/*/wtmpx .
.LP
Linux glibc on the other hand does not use \fIutmpx\fP since its
\fIutmp\fP structure is already large enough.
The functions \fIgetutxent\fP
etc. are aliases for \fIgetutent\fP etc.
.SH "SEE ALSO"
.BR utmp (5),
.BR feature_test_macros (7)
|
