Originální popis anglicky:
endutxent, getutxent, getutxid, getutxline, pututxline, setutxent - user
accounting database functions
Návod, kniha: POSIX Programmer's Manual
#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);
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.
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.
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.
None.
The sizes of the arrays in the structure can be found using the
sizeof
operator.
None.
None.
The Base Definitions volume of IEEE Std 1003.1-2001,
<utmpx.h>
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
.
