getutx(3C) (C Programming Language Utilities) 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]; /* /sbin/inittab id (usually line #) */
char utline[32]; /* device name (console, lnxx) */
pidt utpid; /* process id */
short uttype; /* type of entry */
struct exitstatus {
short etermination; /* Process termination status */
short eexit; /* Process exit status */
} utexit; /* The 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 */
};
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getutx(3C) (C Programming Language Utilities) 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.
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getutx(3C) (C Programming Language Utilities) 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 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.
Each call to either getutxid or getutxline, the routine examines the
static structure before performing more IO. 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 IO for input, but pututxline
uses an unbuffered write to avoid race conditions between processes
trying to modify the utmpx and wtmpx files.
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