getutx(3C)

NAME
     getutx: getutxent, getutxid, getutxline, pututxline, setutxent,
     endutxent, utmpxname, getutmp, getutmpx, updwtmp, updwtmpx - access utmpx
     (extended utmp) file entry

SYNOPSIS
     #include <utmpx.h>

     struct utmpx *getutxent (void);

     struct utmpx *getutxid (const struct utmpx *id);

     struct utmpx *getutxline (const struct utmpx *line);

     struct utmpx *pututxline (const struct utmpx *utmpx);

     void setutxent (void);

     void endutxent (void);

     int utmpxname (const char *file);

     void getutmp (struct utmpx *utmpx, struct utmp *utmp);

     void getutmpx (struct utmp *utmp, struct utmpx *utmpx);

     void updwtmp (char *wfile, struct utmp *utmp);

     void updwtmpx (char *wfilex, struct utmpx *utmpx);

DESCRIPTION
     getutxent, getutxid, and getutxline each return a pointer to a utmpx
     structure:

          struct     utmpx {
               char     ut_user[32];   /* user login name */
               char     ut_id[4];      /* /etc/inittab id (usually */
                                       /* line #) */
               char     ut_line[32];   /* device name (console, lnxx) */
               pid_t    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 */
               struct   timeval ut_tv; /* time entry was made */
               long     ut_session;    /* session ID, used for windowing */
               long     pad[5];        /* reserved for future use */
               short    ut_syslen;     /* length of ut_host including NULL */
               char     ut_host[257];  /* host name, if remote */
          };
     getutxent reads the next entry from a utmpx-like file.  If the file is
     not already open, it opens it.  If it reaches the end of the file, it
     fails.

     getutxid searches forward from the current point in the utmpx 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 getutxid 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.

     getutxline searches forward from the current point in the utmpx 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.

     pututxline writes the supplied utmpx structure into the utmpx file.  It
     uses getutxid 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 pututxline will have searched for the proper entry using one of
     the getutx routines.  If so, pututxline will not search.  If pututxline
     does not find a matching slot for the new entry, it will append a new
     entry to the end of the file.  It returns a pointer to the utmpx
     structure.

     setutxent 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.

     endutxent closes the currently open file.

     utmpxname allows the user to change the name of the file examined, from
     /var/adm/utmpx to any other file.  It is most often expected that this
     other file will be /var/adm/wtmpx.  If the file does not exist, this will
     not be apparent until the first attempt to reference the file is made.
     utmpxname does not open the file.  It just closes the old file if it is
     currently open and saves the new file name.  The new file name must end
     with the character ``x'' to allow the name of the corresponding utmp file
     to be easily obtainable (otherwise an error code of 1 is returned).

     getutmp copies the information stored in the fields of the utmpx
     structure to the corresponding fields of the utmp structure. If the
     information in any field of utmpx does not fit in the corresponding utmp
     field, the data is truncated.

     getutmpx copies the information stored in the fields of the utmp
     structure to the corresponding fields of the utmpx structure.

     updwtmp checks the existence of wfile and its parallel file, whose name
     is obtained by appending an ``x'' to wfile.  If only one of them exists,
     the second one is created and initialized to reflect the state of the
     existing file. utmp is written to wfile and the corresponding utmpx
     structure is written to the parallel file.

     updwtmpx checks the existence of wfilex and its parallel file, whose name
     is obtained by truncating the final ``x'' from wfilex.  If only one of
     them exists, the second one is created and initialized to reflect the
     state of the existing file. utmpx is written to wfilex, and the
     corresponding utmp structure is written to the parallel file.

FILES
     /var/adm/utmp, /var/adm/utmpx
     /var/adm/wtmp, /var/adm/wtmpx

SEE ALSO
     ttyslot(3C), getut(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.

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 getutxid or getutxline, 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 getutxline to search for multiple occurrences it would be
     necessary to zero out the static after each success, or getutxline 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 pututxline (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 getutxent, getutxid, or
     getutxline routines, if the user has just modified those contents and
     passed the pointer back to pututxline.

     These routines use buffered standard I/O for input, but pututxline uses
     an unbuffered write to avoid race conditions between processes trying to
     modify the utmpx and wtmpx files.