endutxent(3p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

ENDUTXENT(3P)           POSIX Programmer's Manual          ENDUTXENT(3P)

PROLOG         top

       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.

NAME         top

       endutxent, getutxent, getutxid, getutxline, pututxline, setutxent
       — user accounting database functions

SYNOPSIS         top

       #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         top

       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_line, 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 search for a record as if by getutxid() 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 thread-safe.

RETURN VALUE         top

       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         top

       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         top

       None.

APPLICATION USAGE         top

       The sizes of the arrays in the structure can be found using the
       sizeof operator.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       The Base Definitions volume of POSIX.1‐2017, utmpx.h(0p)

COPYRIGHT         top

       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 .

       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 .

IEEE/The Open Group               2017                     ENDUTXENT(3P)

Pages that refer to this page: utmpx.h(0p)getutxent(3p)pututxline(3p)setutxent(3p)