pyutmp 0.2.1
Python UTMP wrapper for Un*x systems
License: BSD license

Introduction
============

The ``pyutmp`` module provides a Python-oriented interface to the *utmp*
file on Unix-like operating systems. To paraphrase the *Linux Programmer's
Manual* page *utmp*\ (5), the *utmp* file allows one to discover information
about who is currently using (i.e., is logged into) the system. The *utmp*
file is a series of entries whose structure is typically defined by the
``utmp.h`` C header file.

This module provides an read-only interface to the underlying operating
system's C *utmp* API.

Interface and Usage
===================

The ``pyutmp`` module supplies two classes: UtmpFile and Utmp. A
UtmpFile object represents the open *utmp* file; when you iterate over a
UtmpFile object, it yields successive Utmp objects. For example:

::

    from pyutmp import UtmpFile
    import time

    for utmp in UtmpFile():
        # utmp is a Utmp object
        if utmp.ut_user_process:
            print '%s logged in at %s on tty %s' % (utmp.ut_user, time.ctime(utmp.ut_time), utmp.ut_line)


UtmpFile
--------

In addition to the ``__iter__()`` generator method, allowing iteration over
the contents of the *utmp* file, the UtmpFile class also provides a
``rewind()`` method that permits you to reset the file pointer to the top
of the file. See the class documentation for details.

Utmp
----

The fields of the Utmp class are operating system-dependent. However, they
will *always* include at least the following fields:

+---------------------+-----------+----------------------------------------+
| Field               | Type      | Description                            |
+=====================+===========+========================================+
| ``ut_user``         | ``str``   | The user associated with the *utmp*    |
|                     |           | entry, if any.                         |
+---------------------+-----------+----------------------------------------+
| ``ut_line``         | ``str``   | The tty or pseudo-tty associated with  |
|                     |           | the entry, if any. In this API, the    |
|                     |           | line will *always* be the full path to |
|                     |           | the device.                            |
+---------------------+-----------+----------------------------------------+
| ``ut_host``         | ``str``   | The host name associated with the      |
|                     |           | entry, if any.                         |
+---------------------+-----------+----------------------------------------+
| ``ut_time``         | timestamp | The timestamp associated with the      |
|                     |           | entry. This timestamp is in the form   |
|                     |           | returned by ``time.time()`` and may be |
|                     |           | passed directly to methods like        |
|                     |           | ``time.ctime()``.                      |
+---------------------+-----------+----------------------------------------+
| ``ut_user_process`` | ``bool``  | Whether or not the *utmp* entry is a   |
|                     |           | user process (as opposed to a reboot or|
|                     |           | some other system event).              |
+---------------------+-----------+----------------------------------------+
    
On some operating systems, other fields may be present. For instance, on
Linux and Solaris systems (and other System V-derived systems), Utmp also
contains the following fields:

+---------------------+-----------+----------------------------------------+
| Optional Field      | Type      | Description                            |
+=====================+===========+========================================+
| ``ut_type``         | ``str``   | The type of the entry, typically one of|
|                     |           | the following string values:           |
|                     |           | "RUN_LVL", "BOOT_TIME", "NEW_TIME",    |
|                     |           | "OLD_TIME", "INIT_PROCESS",            |
|                     |           | "LOGIN_PROCESS", "USER_PROCESS",       |
|                     |           | "DEAD_PROCESS", "ACCOUNTING".          |
|                     |           | See the *utmp*\ (5) manual page for a  |
|                     |           | description of these values            |
+---------------------+-----------+----------------------------------------+
| ``ut_pid``          | ``int``   | Associated process ID, if any.         |
+---------------------+-----------+----------------------------------------+
| ``ut_id``           | ``str``   | The *init*\ (8) ID, or the abbreviated |
|                     |           | tty name.                              |
+---------------------+-----------+----------------------------------------+
| ``ut_exit_code``    | ``int``   | Process exit code, if applicable.      |
+---------------------+-----------+----------------------------------------+
| ``ut_session``      | ``int``   | Session ID, for windowing.             |
+---------------------+-----------+----------------------------------------+
| ``ut_addr``         | ``int``   | IPv4 address of remote host (if        |
|                     | array     | applicable), one octet per array       |
|                     |           | element.                               |
+---------------------+-----------+----------------------------------------+

If you're writing portable code, you should not count on the presence of
those attributes--or, at the very least, you should wrap access to them in
a ``try/catch`` block that catches ``AttributeError``.


Notes
=====

This module has been tested on the following operating systems:

- Ubuntu Linux, version 8.04
- FreeBSD
- Mac OS X 10.4 (Tiger)
- OpenSolaris (2008.05, x86, using the SunStudio 12 compiler suite)

Adding support for other Unix variants should be straightforward.

Restrictions
============

- Access to the *utmp* file is read-only. There is no provision for writing
  to the file.

Copyright and License
=====================

This software is released under a BSD license, adapted from
<http://opensource.org/licenses/bsd-license.php>

Copyright (c) 2008-2010 Brian M. Clapper.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

* Neither the name "clapper.org" nor the names of its contributors may be
  used to endorse or promote products derived from this software without
  specific prior written permission.

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