getutx(3C) UNIX System V(C Development Set) getutx(3C)
NAME
getutx: getutxent, getutxid, getutxline, pututxline, setutxent,
endutxent, utmpxname, getutmp, getutmpx, updwtmp, updwtmpx - access utmpx
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 structure
of the following type:
struct utmpx {
char utuser[32]; /* user login name */
char utid[4]; /* /etc/inittab id (usually */
/* line #) */
char utline[32]; /* device name (console, lnxx) */
pidt utpid; /* process id */
short uttype; /* type of entry */
struct exitstatus {
short etermination; /* termination status */
short eexit; /* exit status */
} utexit; /* exit status of a process
/* marked as DEADPROCESS */
struct timeval uttv; /* time entry was made */
short utsyslen; /* significant length of uthost */
/* including terminating null */
char uthost[257]; /* host name, if remote */
};
10/89 Page 1
getutx(3C) UNIX System V(C Development Set) getutx(3C)
getutxent reads in 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 uttype matching id->uttype if the type
specified is RUNLVL, BOOTTIME, OLDTIME, or NEWTIME. If the type
specified in id is INITPROCESS, LOGINPROCESS, USERPROCESS, or
DEADPROCESS, then getutxid will return a pointer to the first entry
whose type is one of these four and whose ut_id field matches id->utid.
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 LOGINPROCESS or USERPROCESS which
also has a ut_line string matching the line->utline string. If the end
of file is reached without a match, it fails.
pututxline writes out 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 add 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 ``x'' character 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
Page 2 10/89
getutx(3C) UNIX System V(C Development Set) getutx(3C)
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), 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.
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 hurt 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.
10/89 Page 3