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Running `awk' Without Input Files
---------------------------------

   You can also run `awk' without any input files.  If you type the
following command line:

     awk 'PROGRAM'

`awk' applies the PROGRAM to the "standard input", which usually means
whatever you type on the terminal.  This continues until you indicate
end-of-file by typing `Ctrl-d'.  (On other operating systems, the
end-of-file character may be different.  For example, on OS/2 and
MS-DOS, it is `Ctrl-z'.)

   As an example, the following program prints a friendly piece of
advice (from Douglas Adams's `The Hitchhiker's Guide to the Galaxy'),
to keep you from worrying about the complexities of computer
programming.  (`BEGIN' is a feature we haven't discussed yet.):

     $ awk "BEGIN { print \"Don't Panic!\" }"
     -| Don't Panic!

   This program does not read any input.  The `\' before each of the
inner double quotes is necessary because of the shell's quoting
rules--in particular because it mixes both single quotes and double
quotes.(1)

   This next simple `awk' program emulates the `cat' utility; it copies
whatever you type at the keyboard to its standard output. (Why this
works is explained shortly.)

     $ awk '{ print }'
     Now is the time for all good men
     -| Now is the time for all good men
     to come to the aid of their country.
     -| to come to the aid of their country.
     Four score and seven years ago, ...
     -| Four score and seven years ago, ...
     What, me worry?
     -| What, me worry?
     Ctrl-d

   ---------- Footnotes ----------

   (1) Although we generally recommend the use of single quotes around
the program text, double quotes are needed here in order to put the
single quote into the message.