getut(3C)       UNIX System V(C Programming Language Utilities)       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
      getutent, getutid, getutline, and pututline each return a pointer to a
      structure with the following members:

             char       utuser[8];     /* user login name */
             char       utid[4];       /* /etc/inittab id (usually line #) */
             char       utline[12];    /* device name (console, lnxx) */
             short      utpid;         /* process id   */
             short      uttype;        /* type of entry */
             struct     exitstatus {
             } utexit;                 /* exit status of a process */
                                        /* marked as DEADPROCESS */
             timet     uttime;        /* time entry was made */

      The structure exit status includes the following members:

                 short   etermination;      /* termination status */
                 short   eexit;             /* 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 RUNLVL, BOOTTIME, OLDTIME, or NEWTIME.  If the type specified in
      id is INITPROCESS, LOGINPROCESS, USERPROCESS, or DEADPROCESS, then
      getutid will return a pointer to the first entry whose type is one of
      these four and whose utid field matches id->ut_id .  If the end of file
      is reached without a match, it fails.



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getut(3C)       UNIX System V(C Programming Language Utilities)       getut(3C)


      getutline searches forward from the current point in the utmp file until
      it finds an entry of the type LOGINPROCESS or USERPROCESS 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.  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 hurt the contents of the static
      structure returned by the getutent, getutid or getutline routines, if the


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getut(3C)       UNIX System V(C Programming Language Utilities)       getut(3C)


      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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