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endutxent.3p (6627B)

'\" et
.TH ENDUTXENT "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
endutxent,
getutxent,
getutxid,
getutxline,
pututxline,
setutxent
\(em user accounting database functions
.SH SYNOPSIS
.LP
.nf
#include <utmpx.h>
.P
void endutxent(void);
struct utmpx *getutxent(void);
struct utmpx *getutxid(const struct utmpx *\fIid\fP);
struct utmpx *getutxline(const struct utmpx *\fIline\fP);
struct utmpx *pututxline(const struct utmpx *\fIutmpx\fP);
void setutxent(void);
.fi
.SH DESCRIPTION
These functions shall provide access to the user accounting database.
.P
The
\fIgetutxent\fR()
function shall read the next entry from the user accounting database.
If the database is not already open, it shall open it. If it reaches
the end of the database, it shall fail.
.P
The
\fIgetutxid\fR()
function shall search forward from the current point in the database.
If the
.IR ut_type
value of the
.BR utmpx
structure pointed to by
.IR id
is BOOT_TIME, OLD_TIME, or NEW_TIME, then it shall stop when it finds
an
entry with a matching
.IR ut_type
value. If the
.IR ut_type
value is INIT_PROCESS, LOGIN_PROCESS, USER_PROCESS,
or DEAD_PROCESS, then it shall stop when it finds an entry whose type
is one of these four and whose
.IR ut_id
member matches the
.IR ut_id
member of the
.BR utmpx
structure pointed to by
.IR id .
If the end of the database is reached without a match,
\fIgetutxid\fR()
shall fail.
.P
The
\fIgetutxline\fR()
function shall search forward from the current point in the database
until it finds an entry of the type LOGIN_PROCESS or USER_PROCESS which
also has a
.IR ut_line
value matching that in the
.BR utmpx
structure pointed to by
.IR line .
If the end of the database is reached without a match,
\fIgetutxline\fR()
shall fail.
.P
The
\fIgetutxid\fR()
or
\fIgetutxline\fR()
function may cache data. For this reason, to use
\fIgetutxline\fR()
to search for multiple occurrences, the application shall zero out the
static data after each success, or
\fIgetutxline\fR()
may return a pointer to the same
.BR utmpx
structure.
.P
There is one exception to the rule about clearing the structure before
further reads are done. The implicit read done by
\fIpututxline\fR()
(if it finds that it is not already at the correct place in the user
accounting database) shall not modify the static structure returned by
\fIgetutxent\fR(),
\fIgetutxid\fR(),
or
\fIgetutxline\fR(),
if the application has modified this structure and passed the
pointer back to
\fIpututxline\fR().
.P
For all entries that match a request, the
.IR ut_type
member indicates the type of the entry. Other members of the entry
shall contain meaningful data based on the value of the
.IR ut_type
member as follows:
.TS
box center tab(!);
cB | cB
l | l.
ut_type Member!Other Members with Meaningful Data
_
EMPTY!No others
BOOT_TIME!\fIut_tv\fP
OLD_TIME!\fIut_tv\fP
NEW_TIME!\fIut_tv\fP
USER_PROCESS!\fIut_id\fP, \fIut_user\fP (login name of the user), \fIut_line\fP, \fIut_pid\fP, \fIut_tv\fP
INIT_PROCESS!\fIut_id\fP, \fIut_pid\fP, \fIut_tv\fP
LOGIN_PROCESS!T{
.IR ut_id ,
.IR ut_user
(implementation-defined name of the login process),
.IR ut_line ,
.IR ut_pid ,
.IR ut_tv
T}
DEAD_PROCESS!\fIut_id\fP, \fIut_pid\fP, \fIut_tv\fP
.TE
.P
An implementation that provides extended security controls may impose
implementation-defined restrictions on accessing the user accounting
database. In particular, the system may deny the existence of some or
all of the user accounting database entries associated with users other
than the caller.
.P
If the process has appropriate privileges, the
\fIpututxline\fR()
function shall write out the structure into the user accounting
database. It shall search for a record as if by
\fIgetutxid\fR()
that satisfies the request. If this search succeeds, then the entry
shall be replaced. Otherwise, a new entry shall be made at the end of
the user accounting database.
.P
The
\fIendutxent\fR()
function shall close the user accounting database.
.P
The
\fIsetutxent\fR()
function shall reset the input to the beginning of the database. This
should be done before each search for a new entry if it is desired that
the entire database be examined.
.P
These functions need not be thread-safe.
.SH "RETURN VALUE"
Upon successful completion,
\fIgetutxent\fR(),
\fIgetutxid\fR(),
and
\fIgetutxline\fR()
shall return a pointer to a
.BR utmpx
structure containing a copy of the requested entry in the user
accounting database. Otherwise, a null pointer shall be returned.
.P
The return value may point to a static area which is overwritten by a
subsequent call to
\fIgetutxid\fR()
or
\fIgetutxline\fR().
.P
Upon successful completion,
\fIpututxline\fR()
shall return a pointer to a
.BR utmpx
structure containing a copy of the entry added to the user accounting
database. Otherwise, a null pointer shall be returned.
.P
The
\fIendutxent\fR()
and
\fIsetutxent\fR()
functions shall not return a value.
.SH ERRORS
No errors are defined for the
\fIendutxent\fR(),
\fIgetutxent\fR(),
\fIgetutxid\fR(),
\fIgetutxline\fR(),
and
\fIsetutxent\fR()
functions.
.P
The
\fIpututxline\fR()
function may fail if:
.TP
.BR EPERM
The process does not have appropriate privileges.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
The sizes of the arrays in the structure can be found using the
.IR sizeof
operator.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<utmpx.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .