getut(3C) getut(3C)
getut: getutent, getutid, getutline, pututline, setutent, endutent,
utmpname - access utmp file entry
#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);
NOTE: these routines are all obsolete and are provided for backward
compatibility only. All access to or modification of these files must be
done via the getutx(3C) set of interfaces.
getutent, getutid, getutline, and pututline each return a pointer to a
utmp structure:
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; /* termination status */
short e_exit; /* exit status */
} ut_exit; /* exit status of a process marked */
/* as DEAD_PROCESS */
time_t ut_time; /* time entry was made */
};
getutent reads 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 last entry read or, if no entries have
been read, from the first entry 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
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getut(3C) getut(3C)
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 last entry read or, if no entries
have been read, from the first entry 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 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 there. 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 returns 1.
/var/adm/utmp
/var/adm/wtmp
getutx(3C), ttyslot(3C), utmp(4), utmpx(4).
A null pointer is returned upon failure to read, whether for permissions
or having reached the end of file, or upon failure to write.
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.
These routines all assume the existence of "utmpx" like file. Many won't
function properly unless such a file exists.
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getut(3C) getut(3C)
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 alter 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.
getutent, getutid, getutline, and pututline, place file locks on files
used during function execution. File locks are not held across calls to
these or other functions, but signals may interrupt the execution of
these functions allowing file locks to be held. When using these
functions where a signal may interrupt function execution, endutent
should be called by signal handlers to release any file locks acquired by
an interrupted function.
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