getutx(3G) getutx(3G)
NAME
getutx: getutxent, getutxid, getutxline, pututxline,
setutxent, endutxent, utmpxname, getutmp, getutmpx, updwtmp,
updwtmpx - access utmpx file entry
SYNOPSIS
cc [flag . . . ] file . . . -lgen [library] . . .
#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, getutxline, and pututxline each return a
pointer to a utmpx structure. [See utmpx(4).]
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 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 returns 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 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.
Copyright 1994 Novell, Inc. Page 1
getutx(3G) getutx(3G)
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 0 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. If neither file exists nothing
will happen.
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
Copyright 1994 Novell, Inc. Page 2
getutx(3G) getutx(3G)
structure is written to the parallel file. If neither file
exists nothing will happen.
Files
/var/adm/utmp, /var/adm/utmpx
/var/adm/wtmp, /var/adm/wtmpx
Errors
A null pointer is returned upon failure to read, whether for
permissions or having reached the end of file, or upon failure
to write.
REFERENCES
getut(3G), ttyslot(3C), utmp(4), utmpx(4)
NOTICES
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.
Copyright 1994 Novell, Inc. Page 3