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NAME
endutxent, getutxent, getutxid, getutxline, pututxline, setutxent - user accounting
database functions
SYNOPSIS
#include <utmpx.h>
void endutxent(void);
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);
DESCRIPTION
These functions shall provide access to the user accounting database.
The getutxent() 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.
The getutxid() function shall search forward from the current point in the database. If
the ut_type value of the utmpx structure pointed to by id is BOOT_TIME, OLD_TIME, or
NEW_TIME, then it shall stop when it finds an entry with a matching ut_type value. If the
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 ut_id member matches
the ut_id member of the utmpx structure pointed to by id. If the end of the database is
reached without a match, getutxid() shall fail.
The getutxline() 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 ut_line
value matching that in the utmpx structure pointed to by line. If the end of the database
is reached without a match, getutxline() shall fail.
The getutxid() or getutxline() function may cache data. For this reason, to use
getutxline() to search for multiple occurrences, the application shall zero out the static
data after each success, or getutxline() may return a pointer to the same utmpx structure.
There is one exception to the rule about clearing 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 user accounting database) shall not modify the static structure
returned by getutxent(), getutxid(), or getutxline(), if the application has modified this
structure and passed the pointer back to pututxline().
For all entries that match a request, the ut_type member indicates the type of the entry.
Other members of the entry shall contain meaningful data based on the value of the ut_type
member as follows:
ut_type Member Other Members with Meaningful Data
EMPTY No others
BOOT_TIME ut_tv
OLD_TIME ut_tv
NEW_TIME ut_tv
USER_PROCESS ut_id, ut_user (login name of the user),
ut_line, ut_pid, ut_tv
INIT_PROCESS ut_id, ut_pid, ut_tv
LOGIN_PROCESS ut_id, ut_user (implementation-defined
name of the login process), ut_pid,
ut_tv
DEAD_PROCESS ut_id, ut_pid, ut_tv
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.
If the process has appropriate privileges, the pututxline() function shall write out the
structure into the user accounting database. It shall use getutxid() to search for a
record 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.
The endutxent() function shall close the user accounting database.
The setutxent() 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.
These functions need not be reentrant. A function that is not required to be reentrant is
not required to be thread-safe.
RETURN VALUE
Upon successful completion, getutxent(), getutxid(), and getutxline() shall return a
pointer to a utmpx structure containing a copy of the requested entry in the user
accounting database. Otherwise, a null pointer shall be returned.
The return value may point to a static area which is overwritten by a subsequent call to
getutxid() or getutxline().
Upon successful completion, pututxline() shall return a pointer to a utmpx structure
containing a copy of the entry added to the user accounting database. Otherwise, a null
pointer shall be returned.
The endutxent() and setutxent() functions shall not return a value.
ERRORS
No errors are defined for the endutxent(), getutxent(), getutxid(), getutxline(), and
setutxent() functions.
The pututxline() function may fail if:
EPERM The process does not have appropriate privileges.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The sizes of the arrays in the structure can be found using the sizeof operator.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
The Base Definitions volume of IEEE Std 1003.1-2001, <utmpx.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .