NAME

getutent, getutid, getutline, pututline, setutent, endutent, utmpname − access utmp file entry

SYNOPSIS

#include <types.h>
#include <utmp.h>

struct utmp ∗getutent ( )

struct utmp ∗getutid (id)
struct utmp ∗id;

struct utmp ∗getutline (line)
struct utmp ∗line;

void pututline (utmp)
struct utmp ∗utmp;

void setutent ( )

void endutent ( )

void utmpname (file)
char ∗file;

HP-UX COMPATIBILITY

Level: HP-UX/RUN ONLY

Origin: System V

DESCRIPTION

Getutent, getutid and getutline each return a pointer to a structure of the following type:

structutmp {
charut_user[8];/∗ User login name ∗/
charut_id[4];/∗ /etc/inittab id (usually line #) ∗/
charut_line[12];/∗ device name (console, lnxx) ∗/
shortut_pid;/∗ process id ∗/
shortut_type;/∗ type of entry ∗/
structexit_status {
    short    e_termination; /∗ Process termination status ∗/
    short    e_exit;/∗ Process exit status ∗/
} ut_exit;/∗ The exit status of a process
∗ marked as DEAD_PROCESS. ∗/
time_tut_time;/∗ time entry was made ∗/
};

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 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 getutid 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.

Getutline searches forward from the current point in the utmp 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. 

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. 

Setutent 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. 

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. 

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. 

COMMENTS

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 getutid or getutline sees the routine examine 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 after each success, or getutline would just return the same pointer over and over again.  There is one exception to the rule about removing 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 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. 

Hewlett-Packard  —  last mod. May 11, 2021