GETUT(3C-SVR3)      RISC/os Reference Manual       GETUT(3C-SVR3)



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

SYNOPSIS
     #include <utmp.h>

     struct utmp *getutent ( )

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

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

     void pututline (utmp)
     struct utmp *utmp;

     void setutent ( )

     void endutent ( )

     void utmpname (file)
     char *file;

DESCRIPTION
     getutent, getutid and getutline each return a pointer to a
     structure of the following type:

          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; /* Process termination status */
                     short      e_exit;        /* Process exit status */
                 } ut_exit;                    /* The exit status of a process
                                                * marked as DEAD_PROCESS. */
                 time_t     ut_time;           /* time entry was made */
          };

     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,



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GETUT(3C-SVR3)      RISC/os Reference Manual       GETUT(3C-SVR3)



     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 which 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.

     setutent resets the input stream to the beginning of the
     file.  This 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 /etc/utmp to any other file.  It is most
     often expected that this other file will be /etc/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.

FILES
     /etc/utmp
     /etc/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.  Each call to either getutid or getutline
     sees the routine examine the static structure before per-
     forming more I/O.  If the contents of the static structure



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GETUT(3C-SVR3)      RISC/os Reference Manual       GETUT(3C-SVR3)



     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
     after each success, or getutline would just return the same
     pointer over and over again.  There is one exception to the
     rule about removing 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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