getut(3)
_________________________________________________________________
getutent, getutid, getutline, pututline, setutent, Subroutine
endutent, utmpname
access utmp file entry
_________________________________________________________________
SYNTAX
#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 */
};
DG/UX 4.00 Page 1
Licensed material--property of copyright holder(s)
getut(3)
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 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 in
the file if it is not already there. It is expected that 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 you
want to examine the entire file.
Endutent closes the currently open file.
Utmpname lets you change the name of the file examined to
something other than /etc/utmp. This other file will usually be
/etc/wtmp. Bad filenames go undetected until the first attempt
to reference the file. Utmpname does not open the file. It just
closes the old file if it is open and saves the new filename.
FILES
/etc/utmp
/etc/wtmp
SEE ALSO
ttyslot(3C), utmp(4).
DG/UX 4.00 Page 2
Licensed material--property of copyright holder(s)
getut(3)
DIAGNOSTICS
A NULL pointer is returned upon failure to read (bad permissions,
end of file, failure to write).
COMMENTS
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 structure match what it is searching for,
it looks no further.
Therefore, to use getutline to search for multiple occurrences,
you must zero out the static structure after each success, or
getutline will 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 you have 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.
DG/UX 4.00 Page 3
Licensed material--property of copyright holder(s)