написать записи utmp и wtmp (write utmp and wtmp entries)
Имя (Name)
login, logout - write utmp and wtmp entries
Синопсис (Synopsis)
#include <utmp.h>
void login(const struct utmp *ut);
int logout(const char *ut_line);
Link with -lutil.
Описание (Description)
The utmp file records who is currently using the system. The
wtmp file records all logins and logouts. See utmp(5).
The function login() takes the supplied struct utmp, ut, and
writes it to both the utmp and the wtmp file.
The function logout() clears the entry in the utmp file again.
GNU details
More precisely, login() takes the argument ut struct, fills the
field ut->ut_type (if there is such a field) with the value
USER_PROCESS, and fills the field ut->ut_pid (if there is such a
field) with the process ID of the calling process. Then it tries
to fill the field ut->ut_line. It takes the first of stdin,
stdout, stderr that is a terminal, and stores the corresponding
pathname minus a possible leading /dev/ into this field, and then
writes the struct to the utmp file. On the other hand, if no
terminal name was found, this field is filled with "???" and the
struct is not written to the utmp file. After this, the struct
is written to the wtmp file.
The logout() function searches the utmp file for an entry
matching the ut_line argument. If a record is found, it is
updated by zeroing out the ut_name and ut_host fields, updating
the ut_tv timestamp field and setting ut_type (if there is such a
field) to DEAD_PROCESS.
Возвращаемое значение (Return value)
The logout() function returns 1 if the entry was successfully
written to the database, or 0 if an error occurred.
Файлы (Files)
/var/run/utmp
user accounting database, configured through _PATH_UTMP in
<paths.h>
/var/log/wtmp
user accounting log file, configured through _PATH_WTMP in
<paths.h>
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────┬───────────────┬─────────────────────────────┐
│Interface │ Attribute │ Value │
├──────────────────┼───────────────┼─────────────────────────────┤
│login(), logout() │ Thread safety │ MT-Unsafe race:utent │
│ │ │ sig:ALRM timer │
└──────────────────┴───────────────┴─────────────────────────────┘
In the above table, utent in race:utent signifies that if any of
the functions setutent(3), getutent(3), or endutent(3) are used
in parallel in different threads of a program, then data races
could occur. login() and logout() calls those functions, so we
use race:utent to remind users.
Стандарты (Conforming to)
Not in POSIX.1. Present on the BSDs.
Примечание (Note)
Note that the member ut_user of struct utmp is called ut_name in
BSD. Therefore, ut_name is defined as an alias for ut_user in
<utmp.h>.
Смотри также (See also)
getutent(3), utmp(5)
