GETUT(3C)                                               GETUT(3C)



     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)                                               GETUT(3C)



          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.
          Multiple 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
          performing more I/O.  If the contents of the static



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     GETUT(3C)                                               GETUT(3C)



          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 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.

     ORIGIN
          AT&T V.3



































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