getut(3C)

NAME
     getut: getutent, getutid, getutline, pututline, setutent, endutent,
     utmpname - access utmp file entry

SYNOPSIS
     #include <utmp.h>

     struct utmp *getutent (void);

     struct utmp *getutid (const struct utmp *id);

     struct utmp *getutline (const struct utmp *line);

     struct utmp *pututline (const struct utmp *utmp);

     void setutent (void);

     void endutent (void);

     int utmpname (const char *file);

DESCRIPTION
     NOTE: these routines are all obsolete and are provided for backward
     compatiblity only.  All access to or modification of these files must be
     done via the getutx(3C) set of interfaces.

     getutent, getutid, getutline, and pututline each return a pointer to a
     utmp structure:

          struct utmp {
               char     ut_user[8];      /* user login name */
               char     ut_id[4];        /* /etc/inittab id (usually line#) */
               char     ut_line[12];     /* device name (console, lnxx) */
               short    ut_pid;          /* process id */
               short    ut_type;         /* type of entry */
               struct   exit_status {
                   short    e_termination;    /* termination status */
                   short    e_exit;           /* exit status */
               } ut_exit;                /* exit status of a process marked */
                                         /* as DEAD_PROCESS */
               time_t   ut_time;         /* time entry was made */
          };

     getutent reads the next entry from a utmp-like file.  If the file is not
     already open, it opens it.  If it reaches the end of the file, it fails.

     getutid searches forward from the current point in the utmp file until it
     finds an entry with a ut_type matching id->ut_type if the type specified
     is RUN_LVL, BOOT_TIME, OLD_TIME, or NEW_TIME.  If the type specified in
     id is INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, then
     getutid will return a pointer to the first entry whose type is one of
     these four and whose ut_id field matches id->ut_id.  If the end of file
     is reached without a match, it fails.

     getutline searches forward from the current point in the utmp file until
     it finds an entry of the type LOGIN_PROCESS or USER_PROCESS that also has
     a ut_line string matching the line->ut_line string.  If the end of file
     is reached without a match, it fails.

     pututline writes the supplied utmp structure into the utmp file.  It uses
     getutid to search forward for the proper place if it finds that it is not
     already there.  It is expected that normally the user of pututline will
     have searched for the proper entry using one of the getut routines.  If
     so, pututline will not search.  If pututline does not find a matching
     slot for the new entry, it will add a new entry to the end of the file.
     It returns a pointer to the utmp structure.

     setutent resets the input stream to the beginning of the file.  This
     reset should be done before each search for a new entry if it is desired
     that the entire file be examined.

     endutent closes the currently open file.

     utmpname allows the user to change the name of the file examined, from
     /var/adm/utmp to any other file.  It is most often expected that this
     other file will be /var/adm/wtmp.  If the file does not exist, this will
     not be apparent until the first attempt to reference the file is made.
     utmpname does not open the file.  It just closes the old file if it is
     currently open and saves the new file name.  If the file name given is
     longer than 79 characters, utmpname returns 0.  Otherwise, it returns 1.

FILES
     /var/adm/utmp
     /var/adm/wtmp

SEE ALSO
     getutx(3C), ttyslot(3C), utmp(4), utmpx(4).

DIAGNOSTICS
     A null pointer is returned upon failure to read, whether for permissions
     or having reached the end of file, or upon failure to write.

WARNING
     All changes to /var/adm/wtmp must also be logged in /var/adm/wtmpx.  Most
     commands that extract information from these files silently discard all
     wtmpx entries without corresponding wtmp entries.

     These routines all assume the existence of "utmpx" like file.  Many won't
     function properly unless such a file exists.

NOTES
     The most current entry is saved in a static structure.  Multiple accesses
     require that it be copied before further accesses are made.  On each call
     to either getutid or getutline, the routine examines the static structure
     before performing more I/O.  If the contents of the static structure
     match what it is searching for, it looks no further.  For this reason, to
     use getutline to search for multiple occurrences, it would be necessary
     to zero out the static area after each success, or getutline would just
     return the same structure over and over again.  There is one exception to
     the rule about emptying the structure before further reads are done.  The
     implicit read done by pututline (if it finds that it is not already at
     the correct place in the file) will not alter the contents of the static
     structure returned by the getutent, getutid or getutline routines, if the
     user has just modified those contents and passed the pointer back to
     pututline.

     These routines use buffered standard I/O for input, but pututline uses an
     unbuffered non-standard write to avoid race conditions between processes
     trying to modify the utmp and wtmp files.