#### 29.12.2 XPG User Accounting Database Functions

These functions, described in the X/Open Portability Guide, are declared in the header file `utmpx.h`.

— Data Type: struct utmpx

> The `utmpx` data structure contains at least the following members:

> `short int ut_type`
>   Specifies the type of login; one of `EMPTY`, `RUN_LVL`, `BOOT_TIME`, `OLD_TIME`, `NEW_TIME`, `INIT_PROCESS`, `LOGIN_PROCESS`, `USER_PROCESS` or `DEAD_PROCESS`.
> `pid_t ut_pid`
>   The process ID number of the login process.
> `char ut_line[]`
>   The device name of the tty (without `/dev/`).
> `char ut_id[]`
>   The inittab ID of the process.
> `char ut_user[]`
>   The user's login name.
> `struct timeval ut_tv`
>   Time the entry was made. For entries of type `OLD_TIME` this is the time when the system clock changed, and for entries of type `NEW_TIME` this is the time the system clock was set to.
> In the GNU C Library, `struct utmpx` is identical to `struct utmp` except for the fact that including `utmpx.h` does not make visible the declaration of `struct exit_status`.

The following macros are defined for use as values for the `ut_type` member of the `utmpx` structure. The values are integer constants and are, in the GNU C Library, identical to the definitions in `utmp.h`.

`EMPTY`
  This macro is used to indicate that the entry contains no valid user accounting information.

`RUN_LVL`
  This macro is used to identify the systems runlevel.

`BOOT_TIME`
  This macro is used to identify the time of system boot.

`OLD_TIME`
  This macro is used to identify the time when the system clock changed.

`NEW_TIME`
  This macro is used to identify the time after the system changed.

`INIT_PROCESS`
  This macro is used to identify a process spawned by the init process.

`LOGIN_PROCESS`
  This macro is used to identify the session leader of a logged in user.

`USER_PROCESS`
  This macro is used to identify a user process.

`DEAD_PROCESS`
  This macro is used to identify a terminated process.

The size of the `ut_line`, `ut_id` and `ut_user` arrays can be found using the `sizeof` operator.

— Function: void setutxent (void)

> Preliminary: | MT-Unsafe race:utent | AS-Unsafe lock | AC-Unsafe lock fd | See POSIX Safety Concepts.

> This function is similar to `setutent`. In the GNU C Library it is simply an alias for `setutent`.

— Function: struct utmpx * getutxent (void)

> Preliminary: | MT-Unsafe init race:utent sig:ALRM timer | AS-Unsafe heap lock | AC-Unsafe lock fd mem | See POSIX Safety Concepts.

> The `getutxent` function is similar to `getutent`, but returns a pointer to a `struct utmpx` instead of `struct utmp`. In the GNU C Library it simply is an alias for `getutent`.

— Function: void endutxent (void)

> Preliminary: | MT-Unsafe race:utent | AS-Unsafe lock | AC-Unsafe lock | See POSIX Safety Concepts.

> This function is similar to `endutent`. In the GNU C Library it is simply an alias for `endutent`.

— Function: struct utmpx * getutxid (const struct utmpx *id)

> Preliminary: | MT-Unsafe init race:utent sig:ALRM timer | AS-Unsafe lock heap | AC-Unsafe lock mem fd | See POSIX Safety Concepts.

> This function is similar to `getutid`, but uses `struct utmpx` instead of `struct utmp`. In the GNU C Library it is simply an alias for `getutid`.

— Function: struct utmpx * getutxline (const struct utmpx *line)

> Preliminary: | MT-Unsafe init race:utent sig:ALRM timer | AS-Unsafe heap lock | AC-Unsafe lock fd mem | See POSIX Safety Concepts.

> This function is similar to `getutid`, but uses `struct utmpx` instead of `struct utmp`. In the GNU C Library it is simply an alias for `getutline`.

— Function: struct utmpx * pututxline (const struct utmpx *utmp)

> Preliminary: | MT-Unsafe race:utent sig:ALRM timer | AS-Unsafe lock | AC-Unsafe lock fd | See POSIX Safety Concepts.

> The `pututxline` function is functionally identical to `pututline`, but uses `struct utmpx` instead of `struct utmp`. In the GNU C Library, `pututxline` is simply an alias for `pututline`.

— Function: int utmpxname (const char *file)

> Preliminary: | MT-Unsafe race:utent | AS-Unsafe lock heap | AC-Unsafe lock mem | See POSIX Safety Concepts.

> The `utmpxname` function is functionally identical to `utmpname`. In the GNU C Library, `utmpxname` is simply an alias for `utmpname`.

You can translate between a traditional `struct utmp` and an XPG `struct utmpx` with the following functions. In the GNU C Library, these functions are merely copies, since the two structures are identical.

— Function: int getutmp (const struct utmpx *utmpx, struct utmp *utmp)

> Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

> `getutmp` copies the information, insofar as the structures are compatible, from utmpx to utmp.

— Function: int getutmpx (const struct utmp *utmp, struct utmpx *utmpx)

> Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

> `getutmpx` copies the information, insofar as the structures are compatible, from utmp to utmpx.