getut(3C) DG/UX 5.4.2 getut(3C)
NAME
getut: getutent, getutid, getutline, pututline, setutent, endutent,
utmpname - access utmp file entry
SYNOPSIS
#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);
DESCRIPTION
getutent, getutid, getutline, and pututline each return a pointer to
a structure with the following members:
char utuser[8]; /* user login name */
char utid[4]; /* /sbin/inittab id (usually line #) */
char utline[12]; /* device name (console, lnxx) */
short utpid; /* process id */
short uttype; /* type of entry */
struct exitstatus {
} utexit; /* exit status of a process */
/* marked as DEADPROCESS */
timet uttime; /* time entry was made */
The structure exit status includes the following members:
short etermination; /* termination status */
short eexit; /* exit status */
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 uttype matching id->ut_type if the
type specified is RUNLVL, BOOTTIME, OLDTIME, or NEWTIME. If the
type specified in id is INITPROCESS, LOGINPROCESS, USERPROCESS, or
DEADPROCESS, then getutid will return a pointer to the first entry
whose type is one of these four and whose utid field matches,
character by character, 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
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getut(3C) DG/UX 5.4.2 getut(3C)
until it finds an entry of the type LOGINPROCESS or USERPROCESS
that also has a utline 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 if it finds
that it is not already at the proper place. 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 /etc/utmp to any other file. It is most often expected that
this other file will be /etc/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 will return 1.
FILES
/etc/utmp
/etc/wtmp
SEE ALSO
ttyslot(3C), utmp(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 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 hurt the contents of the static structure returned
by the getutent, getutid or getutline routines, if the user has just
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getut(3C) DG/UX 5.4.2 getut(3C)
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.
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