getutx(3C)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 */
};
Page 1
getutx(3C)getutx(3C)
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 last entry read or, if no entries have
been read, from the first entry 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 last entry read or, if no entries
have been read, from the first entry 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.
Page 2
getutx(3C)getutx(3C)
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 ALSOttyslot(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.
getutxent, getutxid, getutxline, and pututxline, place file locks on the
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, endutxent
should be called by signal handlers to release any file locks acquired by
an interrupted function.
Page 3
getutx(3C)getutx(3C)
Page 4
