utmp(5) File Formats Manual utmp(5) utmp, wtmp - #include utmp , . , , , utmp. : utmp "", ( ) . , utmp , . utmp, (, ; libc): /* Values for ut_type field, below */ #define EMPTY 0 /* Record does not contain valid info (formerly known as UT_UNKNOWN on Linux) */ #define RUN_LVL 1 /* Change in system run-level (see init(1)) */ #define BOOT_TIME 2 /* Time of system boot (in ut_tv) */ #define NEW_TIME 3 /* Time after system clock change (in ut_tv) */ #define OLD_TIME 4 /* Time before system clock change (in ut_tv) */ #define INIT_PROCESS 5 /* Process spawned by init(1) */ #define LOGIN_PROCESS 6 /* Session leader process for user login */ #define USER_PROCESS 7 /* Normal process */ #define DEAD_PROCESS 8 /* Terminated process */ #define ACCOUNTING 9 /* Not implemented */ #define UT_LINESIZE 32 #define UT_NAMESIZE 32 #define UT_HOSTSIZE 256 struct exit_status { /* Type for ut_exit, below */ short e_termination; /* Process termination status */ short e_exit; /* Process exit status */ }; struct utmp { short ut_type; /* Type of record */ pid_t ut_pid; /* PID of login process */ char ut_line[UT_LINESIZE]; /* Device name of tty - "/dev/" */ char ut_id[4]; /* Terminal name suffix, or inittab(5) ID */ char ut_user[UT_NAMESIZE]; /* Username */ char ut_host[UT_HOSTSIZE]; /* Hostname for remote login, or kernel version for run-level messages */ struct exit_status ut_exit; /* Exit status of a process marked as DEAD_PROCESS; not used by Linux init(1) */ /* The ut_session and ut_tv fields must be the same size when compiled 32- and 64-bit. This allows data files and shared memory to be shared between 32- and 64-bit applications. */ #if __WORDSIZE == 64 && defined __WORDSIZE_COMPAT32 int32_t ut_session; /* Session ID (getsid(2)), used for windowing */ struct { int32_t tv_sec; /* Seconds */ int32_t tv_usec; /* Microseconds */ } ut_tv; /* Time entry was made */ #else long ut_session; /* Session ID */ struct timeval ut_tv; /* Time entry was made */ #endif int32_t ut_addr_v6[4]; /* Internet address of remote host; IPv4 address uses just ut_addr_v6[0] */ char __unused[20]; /* Reserved for future use */ }; /* Backward compatibility hacks */ #define ut_name ut_user #ifndef _NO_UT_TIME #define ut_time ut_tv.tv_sec #endif #define ut_xtime ut_tv.tv_sec #define ut_addr ut_addr_v6[0] This structure gives the name of the special file associated with the user's terminal, the user's login name, and the time of login in the form of time(2). String fields are terminated by a null byte ('\0') if they are shorter than the size of the field. init(1) inittab(5). , , init(1) utmp, ut_type DEAD_PROCESS, ut_user, ut_host ut_time , ut_type DEAD_PROCESS RUN_LVL PID, ut_pid. ut_id, init(1) . ut_id inittab, ut_pid ut_time ut_type INIT_PROCESS. mingetty(8) ( agetty(8)) PID, ut_type LOGIN_PROCESS, ut_time, ut_line .login(1), , ut_type USER_PROCESS, ut_time ut_host ut_addr. mingetty(8) ( agetty(8)) login(1), ut_line, ut_pid. init(1) , , utmp ut_pid, ut_type DEAD_PROCESS, ut_user, ut_host ut_time . xterm(1) and other terminal emulators directly create a USER_PROCESS record and generate the ut_id by using the string that suffix part of the terminal name (the characters following /dev/[pt]ty). If they find a DEAD_PROCESS for this ID, they recycle it, otherwise they create a new entry. If they can, they will mark it as DEAD_PROCESS on exiting and it is advised that they null ut_line, ut_time, ut_user, and ut_host as well. telnetd(8) LOGIN_PROCESS , , login(1). telnet, telnetd(8) utmp . The wtmp file records all logins and logouts. Its format is exactly like utmp except that a null username indicates a logout on the associated terminal. Furthermore, the terminal name ~ with username shutdown or reboot indicates a system shutdown or reboot and the pair of terminal names |/} logs the old/new system time when date(1) changes it. wtmp is maintained by login(1), init(1), and some versions of getty(8) (e.g., mingetty(8) or agetty(8)). None of these programs creates the file, so if it is removed, record-keeping is turned off. /var/run/utmp /var/log/wtmp POSIX.1 does not specify a utmp structure, but rather one named utmpx (as part of the XSI extension), with specifications for the fields ut_type, ut_pid, ut_line, ut_id, ut_user, and ut_tv. POSIX.1 does not specify the lengths of the ut_line and ut_user fields. Linux utmpx utmp. Linux. Linux utmp v7/BSD System V; . v7/BSD ; , ut_type, v7/BSD- , , . , . BSD - ut_id. Linux ( System V) ut_id , , . ut_id , utmp . System V, , BSD utmp. Linux BSD , . System V ut_host ut_addr_v6. , utmp , Linux utmp . who(1), utmp . , , . , , , 32- 64- (x86-64, ppc64, s390x ..), ut_tv 32- 64- . ut_session ut_time, . 32- 64- . ut_session int32_t ut_tv int32_t -- tv_sec tv_usec. ut_tv struct timeval, : gettimeofday((struct timeval *) &ut.ut_tv, NULL); : struct utmp ut; struct timeval tv; gettimeofday(&tv, NULL); ut.ut_tv.tv_sec = tv.tv_sec; ut.ut_tv.tv_usec = tv.tv_usec; ac(1), date(1), init(1), last(1), login(1), logname(1), lslogins(1), users(1), utmpdump(1), who(1), getutent(3), getutmp(3), login(3), logout(3), logwtmp(3), updwtmp(3) Azamat Hackimov , Dmitriy Ovchinnikov , Dmitry Bolkhovskikh , Katrin Kutepova , Yuri Kozlov ; GNU (GNU General Public License - GPL, 3 ) , - . - , , <>. Linux man-pages 6.8 2 2024 . utmp(5)