GETUT(3C-SVR4)      RISC/os Reference Manual       GETUT(3C-SVR4)



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
     getutent, getutid, getutline, and pututline each return a
     pointer to a structure with the following members:

           char       ut_user[8];     /* user login name */
           char       ut_id[4];       /* /sbin/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 {
           } ut_exit;                 /* exit status of a process */
                                      /* marked as DEAD_PROCESS */
           time_t     ut_time;        /* time entry was made */

     The structure exit status includes the following members:

               short   e_termination;      /* termination status */
               short   e_exit;             /* exit status */

     getutent reads in 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



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GETUT(3C-SVR4)      RISC/os Reference Manual       GETUT(3C-SVR4)



     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 out 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 at the proper
     place.  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 will return 1.

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

SEE ALSO
     ttyslot(3C), utmp(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.

NOTES
     The most current entry is saved in a static structure.  Mul-
     tiple accesses require that it be copied before further
     accesses are made.  On each call to either getutid or getut-
     line, the routine examines the static structure before per-
     forming more I/O.  If the contents of the static structure



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     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 hurt 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.






































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