1getutent(3C) Standard C Library Functions getutent(3C)
2
6 getutent, getutid, getutline, pututline, setutent, endutent, utmpname -
7 user accounting database functions
8
10 #include <utmp.h>
11 struct utmp *getutent(void);
13 struct utmp *getutid(const struct utmp *id);
16 struct utmp *getutline(const struct utmp *line);
19 struct utmp *pututline(const struct utmp *utmp);
22 void setutent(void);
25 void endutent(void);
28 int utmpname(const char *file);
31
34 These functions provide access to the user accounting database, utmp.
35 Entries in the database are described by the definitions and data
36 structures in <utmp.h>.
37 The utmp structure contains the following members:
40 char ut_user[8]; /* user login name */
42 char ut_id[4]; /* /sbin/inittab id */
43 /* (usually line #) */
44 char ut_line[12]; /* device name (console, lnxx) */
45 short ut_pid; /* process id */
46 short ut_type; /* type of entry */
47 struct exit_status ut_exit; /* exit status of a process */
48 /* marked as DEAD_PROCESS */
49 time_t ut_time; /* time entry was made */
50 The structure exit_status includes the following members:
54 short e_termination; /* termination status */
56 short e_exit; /* exit status */
57 getutent()
60 The getutent() function reads in the next entry from a utmp database.
61 If the database is not already open, it opens it. If it reaches the
62 end of the database, it fails.
63 getutid()
65 The getutid() function searches forward from the current point in the
66 utmp database until it finds an entry with a ut_type matching
67 id->ut_type if the type specified is RUN_LVL, BOOT_TIME, DOWN_TIME,
68 OLD_TIME, or NEW_TIME. If the type specified in id is INIT_PROCESS,
69 LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, then getutid() will
70 return a pointer to the first entry whose type is one of these four and
71 whose ut_id member matches id->ut_id. If the end of database is reached
72 without a match, it fails.
73 getutline()
75 The getutline() function searches forward from the current point in the
76 utmp database until it finds an entry of the type LOGIN_PROCESS or
77 ut_line string matching the line->ut_line string. If the end of data‐
78 base is reached without a match, it fails.
79 pututline()
81 The pututline() function writes the supplied utmp structure into the
82 utmp database. It uses getutid() to search forward for the proper
83 place if it finds that it is not already at the proper place. It is
84 expected that normally the user of pututline() will have searched for
85 the proper entry using one of the these functions. If so, pututline()
86 will not search. If pututline() does not find a matching slot for the
87 new entry, it will add a new entry to the end of the database. It
88 returns a pointer to the utmp structure. When called by a non-root
89 user, pututline() invokes a setuid() root program to verify and write
90 the entry, since the utmp database is normally writable only by root.
91 In this event, the ut_name member must correspond to the actual user
92 name associated with the process; the ut_type member must be either
93 USER_PROCESS or DEAD_PROCESS; and the ut_line member must be a device
94 special file and be writable by the user.
95 setutent()
97 The setutent() function resets the input stream to the beginning. This
98 reset should be done before each search for a new entry if it is
99 desired that the entire database be examined.
100 endutent()
102 The endutent() function closes the currently open database.
103 utmpname()
105 The utmpname() function allows the user to change the name of the data‐
106 base file examined to another file. If the file does not exist, this
107 will not be apparent until the first attempt to reference the file is
108 made. The utmpname() function does not open the file but closes the
109 old file if it is currently open and saves the new file name.
110
112 A null pointer is returned upon failure to read, whether for permis‐
113 sions or having reached the end of file, or upon failure to write. If
114 the file name given is longer than 79 characters, utmpname() returns 0.
115 Otherwise, it returns 1.
116
118 These functions use buffered standard I/O for input, but pututline()
119 uses an unbuffered non-standard write to avoid race conditions between
120 processes trying to modify the utmp and wtmp databases.
121 Applications should not access the utmp and wtmp databases directly,
124 but should use these functions to ensure that these databases are main‐
125 tained consistently. Using these functions, however, may cause applica‐
126 tions to fail if user accounting data cannot be represented properly in
127 the utmp structure (for example, on a system where PIDs can exceed
128 32767). Use the functions described on the getutxent(3C) manual page
129 instead.
130
132 See attributes(5) for descriptions of the following attributes:
133 ┌─────────────────────────────┬─────────────────────────────┐
138 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
139 ├─────────────────────────────┼─────────────────────────────┤
140 │MT-Level │Unsafe │
141 └─────────────────────────────┴─────────────────────────────┘
142
144 getutxent(3C), ttyslot(3C), utmpx(4), attributes(5)
145
147 The most current entry is saved in a static structure. Multiple
148 accesses require that it be copied before further accesses are made. On
149 each call to either getutid() or getutline(), the function examines the
150 static structure before performing more I/O. If the contents of the
151 static structure match what it is searching for, it looks no further.
152 For this reason, to use getutline() to search for multiple occurrences,
153 it would be necessary to zero out the static area after each success,
154 or getutline() would just return the same structure over and over
155 again. There is one exception to the rule about emptying the structure
156 before further reads are done. The implicit read done by pututline()
157 (if it finds that it is not already at the correct place in the file)
158 will not hurt the contents of the static structure returned by the
159 getutent(), getutid() or getutline() functions, if the user has just
160 modified those contents and passed the pointer back to pututline().
161SunOS 5.11 27 Oct 1998 getutent(3C)