Miscellaneous
==============================

There are many command in linux. I certainly do not know them all.
There are two amusing and useful commands you should know about before
we quit. One is ``date``, which prints the current date and time
to the command line and is useful for time stamping files.  Once you
know more about scripting, you include a line like: ::

% date

and the date and time will be printed to whatever file is collecting
your output. ``date`` has many formatting options for its output. See
the ``man`` pages for all the options. For example, to display the Julian
date (day of the year, switch j) issue: ::

% date +%j

Note the plus (+) sign and the percent (%) sign.

Text can be included in the output by enclosing the text and the
switch(es) in single quotation marks. The plus sign(+) must be the
first character quoted. For example, to display the seconds since 1
January 1970, issue: ::

% date '+The number of seconds since New Years, 1970 is %s'

See if you can include text and multiple switches together in the same
output.

A related command is ``ddate``. This seems to just be nerd humor: ::

% ddate

That was not the second command I was talking about. What I was
intending is the calendar command ``cal`` which will produce a
Gregorian calendar for whatever year you specify, even for years that
did not use the Julian calendar. For example, ::

% cal 1776

will tell you the day of the week for the American Independence
Day. If you just wanted to see the month of July you could just issue:
::

% cal 7 1776

and see that Thursday was a big day that month.

Now for a little fun with ``cal``. See if you can determine the rule
for determining which years are leap years. You may think, as I once
did, that any year evenly divisible by 4 is a leap year. You would be
in error. That rule is close but there are some important
modifications. Here are some hints: ::

% cal 2 1900
% cal 2 1984
% cal 2 2000
% cal 2 2500

Also, the year 1700 is anomalous. Good luck!!


If you made it this far, and retained a decent amount, you are a
mighty penguin.  There are many linux online resources on
internet. Have fun.

.. image:: penguin.png
   :height: 600
   :width:  600
   :align: center
   :scale: 50
   




Summary
-------

===========         ==========
Command             Meaning
===========         ==========
date                display date and time
date +%d            display current day of month-01 to 31
cal 1905            display 12 month calendar for 1905
cal 3 1882          display birth month of mathematician emmy noether
===========         ==========